Slam Punk the Phoenix Hawk pilot was not the sharpest tool in the shed. The series of events that lead to his demise clearly illustrated this fact.
It wasn't enough that he leaped over a hill ahead of the rest of his team. No, he had to leap down and land his little P-Hawk in front of a pair of good ol' BLR-1G Battlemasters. Presented with a fresh target at close range and nothing else in line-of-sight, they went to town, literally disarming his mech. Left with no weapons, he decided on the next best option, launching a Death From Above attack on one of the B-Mers.
Yeah, a 45-ton Phoenix Hawk tries to DFA an 85-ton Battlemaster. The logic here is staggering. Between the impact and his subsequent fall, he took far more damage then his target did. The subsequent retaliation left his mech crippled, but the pilot more-or-less unharmed. He took steps to remedy this.
Running willy-nilly across the battlefield, he broke into the bad guy base that was under attack. Inside, he found one of their B-Mers, badly damaged and shut down. With nothing better to do and is own mech a wreck, he climbed in and tried to steal it.
Only he failed the Ident code and the mech's security system locked him out. Did I mention that he had none of the skills or equipment he'd need to bypass it? Well, you get the picture.
So, stuck inside the cockpit of an enemy mech, powered down in the middle of their (rapidly crumbling) fortress, he took the only logical way out. He pulled out his Kambrook Laser Pistol and blew his own brains out.