I think he is a bot too (played against him over 200 games). After the thread about how gto scammers are working im more sure. There you can see that the developer specificly asks the players to not wait in such an obvious spots (like checking flop OOP in a limped/raised spots), because the bot can't fastcheck (needs to send the log files to the second computer from the screen, analyzing the data, searching for the right board textures, etc which takes few seconds). So basically in these 200 games he did not have a single fast check at all, even you think through many decision at least few of them will be automatic and you do them fast.
All in all he is making all those mistakes which a good bot developer trying to avoid which makes me think he is a bad bot, and nothing else.
I have seen him checking back preflop low PP on shortstack (8bb and under). It's a really complex preflop GTO move, which even 500s regs lack of.
And his behaviour also really suspicious like they mentioned above (he is not opensitting etc, and playing 4-5 hours straight without any mistake plus his play is very linear).
Sadly Partypoker is still very unsufficient to catch bots