I believe in spawn killing like I believe in kill stealing. Which is not much at all. If someone states they are going afk and I see them standing in spawn I will leave them alone. Otherwise.... I see you I go after you. That simple. I'm not going to let you come up behind me to get me unless I have more urgent objectives in mind like retrieving a stolen flag headed to your base. In situations like those I will toss off a charged fb your way to keep you in spawn (and anyone else spawning with you) there for a couple seconds longer.