Why should they? Its an old game, no need for them to update stuff.
Activision also never updated some huge bugs or exploits.
For Cod2: I would wish they bring out some source codes (not complete game) so you easy can change some hard coded stuff, also to fix some huge bugs that u can't fix because its hard coded.
About PB:
Pb just failed complete in my eyes, it was never that usefull! There are more usefull anti cheat tools that could easy be implemented to cod2, also with an auto update function.