[I don’t know the current SJW definition of the word “problematic” so I’m going with what the dictionary explains, which is smtg “constituting or presenting a problem or difficulty.”]
So AR had commented thusly on her FB, 2014 (might be a different year):

It’s true that she used to attack fanfic authors, there was a war on fanfic in the ‘90s…

…but currently she seems to ignore it. Huzzah, right? I think so!
I can’t recall her having an issue with RPers. Not sure why, but maybe she doesn’t see RP as being fanfiction in that it’s a series of responses. There are fics and published works that write from different characters’ POV (Queen of the Damned did that, for example) but seem to devote whole chapters to each POV.
We had a situation recently in which a VC RPer was sent what we now consider to have been Anon-hate that was written to look like a real Cease & Desist letter (which is what we get when AR wants our grubby hands off her precious bbs). We believe it was a particularly cruel way to send Anon-hate.
So I think you’re clear, no problems. Go RP!
However, your friend may have other reservations about RPing, too. There are a lot of things to consider, among which:
- Are you over 18?
- Are you willing to RP with people under 18?
- Are you willing to RP smut and R-rated scenes?
- Are you willing to RP with OC’s and other fandoms?
- Are you willing to RP AU?
- Is your muse a canon or original
character?
- Is your muse multi-ship (can have more than one relationship at a time in different threads)?