It’s certainly odd that she’d post something like this, but let’s keep some things in mind:
This is a personal account, not an official thing. She could post nothing but porn links, and while it wouldn’t be a good idea, she’d be well within her rights to do so.
Anyone who actually gets what the picture is implying has probably seen way worse content than this anyway. It’s just strong innuendo.
As previously noted, she’s probably well aware of the innuendo. She’s an adult, and can lol at suggestive fanart just as well as the rest of us.
Also as noted, Tara has posted tons of suggestive stuff on her twitter, so honestly there’s kind of a precedent for this. Case in point:
