I've only been weaponslocked in PS twice in my entire gaming history: for deliberately TKing hackers over and over as they spawned trying to prevent them from teleporting out of the tubes into the gens of other empires.
That said, I TK'ed far, FAR FAR more friendlies in PS2 by accident than in PS1 and that has everything to do with collissionmodels of vehicles, poor situational awareness due to lack of proper third person (too zoomed in, too low angle) and often are forced by the auto-drive when players don't look where they're going (and the game, unlike in PS1, blames the player spawning a vehicle - in PS1 you simply died as the vpad opened and it counted as a suicide). Maybe they should place signs that say "don't cross here".
People that get grieflocked don't know how to aim and are too busy with themselves rather than take the allies around them into account.