@Evowizard25  
The only ones with capacity for corruption in the nobility are in the royal family.
 
In case you haven’t noticed, the rest are just trendy rich idiots, despite what the fandom thinks of them.

@PonyPon  
Well yeah, it makes sense. The nobility has some corruption, so it’s not exactly safe to tell them that. The main six aren’t that good at keeping secrets for long. One of them would say something. In all honesty, the Princesses have no real reason to give away the Tree’s location unless they absolutely had to. They weren’t aware it was in danger as they didn’t know about Discord’s seeds.
 
While this episode is flawed, and my personal least favorite opener, this wasn’t something I found flawed within context.

@Evowizard25  
But from the people it’s trying to protect?
 
So no one can protect it?
 
This thing is basically their god.

…Why would they publicize this? Wouldn’t it be better to not give away your ace in the whole? The one thing keeping the Everfree Forest at bay? Given how many enemies these two and Equestria as a whole has, I think it would be better to keep it a secret.