I know neoseeker lists it on 360,ps3 and pc but I have a fairly reliable friend who swears he's seen a copy on ps2.
I keep telling him he's wrong but he just won't accept it.

He's wrong. It was never on PS2, and it won't be.

Very wrong, the game came out in 2007 and was released just for PC and 360, it had a year before being released on PS3.

Never been on PS2, which due to being around for around 7-10 years, wouldn't be able to handle Bioshock

The PS2 could not even handle the menu screen. They could make a game that worked on the PS2 but it would not be anything like the 360 version. It would be along the same story line, but look nowhere near as good.

Ps2 would explode after actually having a disc in it that has a real storyline.
Never been, never will be on the PS2.
There's a PS3 version with a few differences but nothing major that'd change the game.
By differences I mean, there's a bonus song, big daddys have a different weapon, as far as I know.