In reality most Thais do not pronounce the R like us Western folks do. Usually, it sounds like: kidipon, sillipon or titipon
Correct.
The 'porn' name ending with the R is a fallacy and a mistransliteration maybe by accident and maybe by some comedian for the purposes of titillation. It is a long 'aw' sound liked in pawn.
Actually there are a lot of Thai words that have the "r" that is actually part of the Thai spelling (raw rua) but is not normally pronounced as an "r" sound.