Hmm. I must have definetely overlooked that.
That seems a bit harsch though? most scenarios already start with 4 spawnpoints, adding one more means 5 which then means you lose the entire game if just 1 Necromancer gets through.
If that should happen too early in the game, just ignore the 'auto-lose'. From that point on, you'll have six permanent spawn points (plus any new necromancer spawn points), which means the game just gets tougher. It is OK to adjust any rule that interferes with having fun. Having fun is the only rule that shouldn't be adjusted.