Without really looking at the rest of the discussion:
Pre-flop: We don't know much about this guy save for "loose passive." which means that he has a very big range to call with here, especially when he is already priced in from the BB. So, pre-flop we just kind of have to trust he is likely behind us, but is calling with a ton of stuff (Ax, K9+,QT+, 22+, lots of suited connectors).
Flop: Well, this seems like a pretty decent board for us. Its somewhat damp with the straight and the flush draw, but not too bad. We bet and are x/r'd by the loose passive player. I think a solid argument could be made for just folding here. A passive player is not likely to x/r with a TP kind of hand. He probably is not going to be doing this as a bluff either. Maybe its something wacky like Axhh that he decided to get silly with (there is always a chance someone just acts out of character for no reason). The other option is that he has QQ and thinks he is ahead. I think the only hands we are beating that might do this are QQ, Axhh and... maybe a straightflush draw like KQhh. Every other hand he has that is x/ring is ahead of us by far (JT, 44, TT, AA). And all of those hands are in his range. And, with the exception of QQ, the hands we are beating we are not beating by much. I don't hate a call here, but I have a hard time thinking we are ahead of his x/r range.
Turn: The A hits, while not the WORST card in the world, its pretty bad. If he has KQhh then we lose, if her has Axhh we lose, if he has QQ we still win... but why tf is he betting? He is loose and passive. At this point you have to recognize that KK is just not going to hop up, and you also have to recognize that if you call here then you are going to be calling another bet on the river. I think without exception this guy will bet that river. He has an on and off switch to aggression, and it is on right now. If you think (for whatever reason) he is doing this with a hand you beat, you should just shove and hope that the weakest part of his range that still beats you will fold....it never will though. fold here.
River: everything just got worse. The couple of hands that maybe you were ahead of that just spazzed out (like QT or something stupid that was somehow still there) are no ahead of you. I guess maybe he was holding... uh J4 and now you are beating him, but lets not be silly. While garbage will show up, you just have to let it go. Good job on that. I think you could have avoided some hurt by folding the flop or the turn though.