This is (or should be considered) spawn killing because you can consider the players "nonspawned" until they exit their spawnroom/building
When players are in the spawn room, they can't affect gameplay beyond chat (which doesn't do much), and so can be considered as still in the "respawn timer" waiting period. Spawnkilling can also be considered as stopping players from being able to affect gameplay intentionally and unfairly, ruining the fun and skill normal gameplay requires.