@Background Pony #4B86  
Doubly so with the whole Trixie incident.

@Amethyst_Crystal  
Still even then, it just makes her look like a hypocritical bitch.

@Background Pony #3AFA  
She sees changelings as dangerous enemies, like the other ponies do.
 
Sure she didn’t have any experience with them herself at that time,  
but she tries to side with Twilight and her friends/family when she can during s6.
 
Although she does visibly relax later during Spike’s song, too.

Why is Starlight angry? _

@Connor Gorden  

 
This might be the most neutral expression Shining Armor has during the song, he’s mostly scowling or snarling even worse.
 
 

I disagree it does look as though shining armor is weighing the merits of forgiveness, though granted I watch through Netflix and this is all I’ve seen of the later episodes, lol( have to say though, his face dose look at the very least, pensive.)

@Cirrus Light  
Yep, that seems pretty much right.

Mama bear Cadance.

@Pagan  
I would say they view them as sort of both. Well, probably a bit different since this episode, but before this it was probably kind of both. The only intelligent changeling they’ve ever seen was the queen - though other reports might have noticed intelligence among the drones, it wouldn’t have been known the exact nature of the intelligence - hivemind or individualistic?
 
That, and there were no allies among them, which makes it kind of clear they were pretty much unanimously ponykind’s enemy. And the one instance they did have of one with a confirmed intelligence they spoke with, was quite malevolent.
 
So in that sense, very much like a wild animal in that they were pretty much a big dangerous thing where every and any one of them have attacked ponies, and unlike wild animals, every encounter they’d had with them had been hostile in nature. So in some senses, a bit worse than wild animals.

@Cirrus Light  

 
Sure it is better repeat another 5 times just to make sure though.  

 
Not really they view them more as a hostile nation than a wild animal.

@Pagan  
They’re an apt metaphor. They fit perfectly for how Equestrians view changelings.

@Cirrus Light  
“mountain lions”  
@Cirrus Light  
“mountain lions”  
@Cirrus Light  
“mountain lions”  
@Cirrus Light  
“mountain lions”  
@Cirrus Light  
“mountain lions”
 
It’s a conspiracy.

@SuperSonic15  
A giant bug-creature that feeds off of love and tried to make your love brain-dead is now trying to eat your baby.
 
Of course Thorax wasn’t actually trying to eat Flurry, but that’s what it looked like, and if a mountain lion is pouncing on my baby, I’m not going to sit there wondering if it’s just being playful.
 
Pretty understandable, really.

@Amethyst_Crystal  
Well, compare her here with her expression after Thorax exposes himself due to being unable to restrain his instincts and moving to protect Flurry Heart from him.
 
The only time I’ve seen Cadance have an expression of that much anger, contempt, and hatred on her face was on the vector of her used in some of Silver Quill’s After the Fact videos when she’s about to beat Silver Quill up for his wisecracks and trolling against her or some of the other characters like the other Princesses or the Mane Six.
 
I’ve tried to compare it to her angry expressions in previous episodes like Three’s a Crowd and Twilight’s Kingdom regarding Discord and Tirek, and she does not look as angry then as she does here with Thorax.

@Background Pony #F2DC  

 
Well, by ‘unusual’ I meant Cadance ‘(almost) never’ looks this way, or so the comment seemed to imply.  
She does tend to be more calm and serene on average than most ponies,  
even if her onscreen appearances involve more disasters and drama than average.  
Definitely gets this stern expression occasionally though.

@Amethyst_Crystal  
“As an aside, someone mentioned Cadance looking unusually angry here.”
 
Get kidnapped, be trapped in a crystal cave for weeks on end and then have your loved dear try to kill you because the villain manipulated them into thinking you’re a changeling…
 
Yeah, I’d be pretty hateful of Changelings too if that happened to me…

Lots of awesome cool discussion here about pony politics, laws, ethics, etc!
 
As an aside, someone mentioned Cadance looking unusually angry here.  
She may not glare nearly as often as other ponies, but she does sometimes still.  
Pretty sure she’s had similar expressions the first time she’s dealt with changelings,  
as well as when she helped defeat King Sombra,  
and as she put up with Discord’s bs.

@Background Pony #7663  
@Cirrus Light  
@Pagan  
I’m willing to accept that theory.

@Background Pony #7663  
That’s about the only way it makes sense.

@Background Pony #7663  
I like that take on it a lot.

The way I see it, this is one of those songs that wasn’t actually a song, in universe.
 
As in, it was a representation of a much more draw out discussion as Spike made his case, wrapped into a song for time.

@Revan0123  
Agreed. Perhaps we’ll find out in the season finale. Until then, it’s all speculation.

@Pagan  
Time will tell…
 
@Pagan  
Yeah, mainly because of all the shift in the status quo that resulted from it.

@Background Pony #F2DC  
But this has been the only episode this season worth discussing.