Sirdude, loss of a booster is bloody crippling too, also aliens will lose very quickly with only one egg.
It is just so painstakingly obvious that this is an issue, on one side you have humans readily accessing the armory (equivalent of evolving for aliens) whenever they want in order to attack/defend, while on the other hand aliens are attempting to defend a base using only dretches as somehow the mere presence of a human disables aliens from evolving in order to defend their base, it just doesn't seem logical forcing aliens to evacuate their own base in order to evolve into something capable of actually defending it.