She does this all the time when asked about products she's promoting- I think it's so rude tbh. As you say- it wouldn't be hard to contact the company for advice to give her followers?Is she an idiot?
A follower asks you about sizing, and you respond with "I'm not sure" and advise to check the site?
Maybe go a step further for your follower, drop MP a message (I'm sure they'll get back to you quickly because you're such an important BA), and give some useful sizing info?
No interest in helping out a plus size follower by the looks of things.