If the defender has no tokens to remove does he automatically take the damage or can he still choose?

Unless it gets faq'd otherwise, no they dont get automatic damage.

Reason:
You fired and theres an enemy ship in arc. He has two choices, take 1 damage or remove all of its focus and evade tokens. There is no limiting condition that it has to actually have tokens, as 0 is a valid number in this game. If it was worded "remove 1 or more" then it would automatically do damage.

Right now its treated as a cost to keep your tokens. If you really want/need that focus token, take a damage or cough it up. Got no tokens? Dont worry about it.

Ah makes sense thanks