I realise that however you could code a radius around the spawn point/area that detects enemies and activates spawn protection for a certain amount of time ( if an enemy is there )
you already have huge advantage when enemy is inside your spawn area, because enemy can't kill you first few seconds (spawn protection). Your idea about extra protection will not fix anything. It will only slow down game and both teams will camp on one spawn area, or another.
P.S. If you have ideas and you want to suggest something, do it in forum.