Yep, that makes perfect sense. She's a known entity to so many, she has to be, and I guess the type of person who worked for SHIELD in the first place won't just shrug and get a janitor's job instead. Actual SHIELD has gone underground and is getting a bad rep, so going where Maria went has to look like a good alternative in that case.

Which then of course seems to go wrong a wee bit via Ultron. -- Tiny little bit. XD

And yep. Not exactly best friends or likely to, like, go grab a beer together, but they did/do respect each other's competence.