Well, one thing is for sure, these servers are packed with bots. Question is, whats the purpose of all that...

Either (as you mentioned), they might be there to cause some havoc. They most likely are the sole reason why other players cant join multiplayer servers or cant even list them. The question still remains, why would anyone waste the electricity, HW and time for blocking access to servers of this dead game.

The more probable option is that they are actually hired to keep the numbers of this game on high values. Then from the steam charts, this game might appear more active than it actually is and it may be the reason why we still see lost souls around here that mysteriously bought this game but are in fact surprised that its an empty place with just bunch of cheaters.

I honestly think that the second option is correct. Perhaps some chinese companies do provide these services. Owner just gives free copies to the second party and then they in return for a reasonable price provide the bots that on the outside appear as actual players.