At the RnRHoF speech, Robert said “Porl” when going thru the list of people who were in the band.
My guess is that it was something like the fact Pearl was Porl while in the band. I suppose it also could have been that RS was flustered, amped, etc. when up there speaking. Things like that can happen. I don't think he would have said "Porl" unless by mistake or if it was done with respect, though. I have never heard of RS treating anyone with anything less than respect (I'm sure it's happened on occasion, as nobody's perfect and everyone gets po'd, but at least not in the public eye).
I have a trans friend and I still refer to her with her original name if the time I'm talking about was before the decision and she isn't present... because I'm sure she wouldn't appreciate that if she was, but it makes it easier for people to understand who and what you're referring to.