Short answer
No. I make this mod to counter the behaviour in spamming a single type of turret. This mod is not about countering every damage type.
Long answer
The primary motivation of this mod is to prevent spamming a single type of turret (e.g., vanilla laser turret and flamethrower turret), where the players do not need anything else. Just spamming laser turrets then can forget about defense certainly leads to boring gameplay. This mod is to counter those "cheesy" defense.
So it is NOT about making a resistant biter for each damage type. It is not fantasy settings that needs a counter to each magic elements. Inclined to that would be more like magic system, instead of biological evolution.
Cannon shells are rather expensive, and inflexible (firing angle) enough to be used as the sole defense. So IMO cannon turrets never need special counter to them.
In-game high level biters already have quite high explosion resistance. I do not think that a explosion immune biter is necessary.
If you are talking about cannon turrets, the AP shells deal no explosion damage, but pure physical damage. So according to you "cover any damage type" logic, do I need a physical immune variant too? Now you can see why I am not buying this logic.
Poison rockets are expensive too (supposedly, yet I do not have time to play any 1.0 or 1.1 games). So I also assume spamming rocket turrets and poison rockets for defense would not be a problem.
If poison rockets have too high damage-per-cost ratio, I would consider nerfing it first.
I will reserve the idea of poison immune aliens for the moment, as I have big doubt on such need.
