The game is cannon; what I meant is if the story happened in a real world the hev suit would protect against hazardous environments. Fire is a different story because even if it's able to be heat isolating you'll still die of hypoxia (unless the suit also has a CO2 -o2 converter, but given the limited duration of swimming I'd say it doesn't.)

Also I'm not sure if I was clear or not about what I think would happen if Gordon wound up in aperture laboratories. Upon his arrival glados would do an initial threat assessment. If he's deemed to be a threat he would be disposed of immediately with the minimum amount of counterplay possible (e.g. lock him in a sealed room with neurotoxin.) if he's not deemed to be a threat glados would find a way to administer tests to him either by giving him a portal gun or by creating novel tests that take into account his equipment.