(interesting to hear that. are you using addbot commands in your bot.cfg, or are you doing this using min_bot and max_bots cvars ?)
sry, you must be using addbot commands, since otherwise you cannot put CT/T differently.
looks like there is no way to avoid respawning at the moment. there is only a command which avoids respawning when there isnt yet any human player on the server ... that'd be joinwhuman_res. but unfortunately no command to avoid respawning at all, that's something for the todo list