I have been trying to get my head around why any other letters at all have been or should be added to "LGB" and, giving him the benefit of the doubt, I think Cantor is making a simple category error.
All the other additions to "LGB" can be framed as category errors. "Error" does not mean that they were accidental; it could be argued that they are faults introduced for political reasons.
By Cantor's logic it would make as much sense to add "P for Pyromania" (really) as "P for Paedophilia".
LGB and H (Heterosexuality) are equal and different to any other erotic attraction or expression because they are the basic categories of sexual attraction to same and/or opposite biological sex - and there only two sexes.
That is the starting point. There could have been other starting points and there might be others in an imagined future but that is irrelevant.
LGB and H are all mutually exclusive:
There are six options:
a) Lesbian
b) Gay Man
c) Bisexual Woman
d) Bisexual Man
e) Heterosexual Woman
f) Heterosexual Man
("Pansexual" is only needed if you want to add in all the Gender Identity options too - I am just keeping it as simple as possible.)
Anything else is a "modifier", whether it has got a "special name" for it (eg. "Transgender", "Gerontophilic") or not.
I could go on but this is much less important than the personal issues being discussed.
There no more needs to be a "P for Paedophile" than an "I for Intersex" a "Q for Queer" an "A for Asexual" or any of the rest of the alphabet soup.
There is LGB and there is H. Full stop.