Miki still does factor. But even if you have him against titans, if there are very few favorable tiles on the board, the team without Miki may still score higher if they got abundant favorable tiles in it.
I think the OP is reporting that before and after firing Miki the tile damage isn’t affected, not that the total damage is unchanged. Obviously total damage depends on board luck with the tiles, but if individual tile damage isn’t affected, then there may be an issue.
I could see the OP’s logic, they could have coded the Mythic Titan to have 0, or -1 so he couldn’t be killed, but given Miki’s special being dependent on the enemy needed higher health, that would mess up the mechanics.
It would be interesting if anyone has reported the same with Ranvir, since his special is affected the same way.