Oh I see what you're saying. That is a legit tactic. Don't spawn if the flag you are set to is being spawn raped (or your forward spawn is being raped). You might have to rejoin the game to get set to a new flag. When people stop spawning on the flag, they should eventually capture it.
I don't see why there should be any justification to let people spawn in with a grace period, I think it's a terrible idea. You need to protect your flags/forward spawn), or else account for it in other ways. If you have half your team (or more) set to spawn at one flag or spawn point, you need to defend it. If you don't, that's your fault and shouldn't have your hand held to get you out of the situation you are responsible for.