In some discussions (political ones especially), Poe's Law applies, oftentimes real people hold real opinions that are as blunt as trolls' opinions.

In the discussed case I have little doubts that the said troll indeed held most of the opinions he has expressed here. To clarify, by "troll" I mean someone who argues for fun of arguing and without caring a bit about the standards of a reasonable discussion; a troll needn't to pretend holding opinions which he in fact doesn't share. (My use of "not being sincere" in the OP might be misleading in this respect.)