Yeah, Byleth doesn't miss the 'was' in that sentence and she dislikes it immensely. Everyone should have the choice to fight, but she knows that isn't always the case. War had ways of erasing options, and it hadn't been either of their choices to be the products of human experimentation, or to be raised as they had.

Perhaps it's best not to dwell on it, as there's nothing that can be done to change the past--only ways to cope with it.

Like fishing.

"It's enjoyable. We could invite the other me as well. I'm sure he'd be interested."