It's not like Captain America has been a Hydra agent all along either…

I agree. It would be an attack on the idea of America. And that's really the point of terrorism, to effect change through violent acts. It's the sort of act that would get us to go to war with someone not really related to said event, but blamed for it anyway.

Given that Kirkman isn't running (for a while at least) that does benefit him. So he can say that and get away with it… for now… I'm sure that Hookstraten won't let him forget that in the future election.

There are also DNA samplers that are portable and can be used with a laptop. Given their situation, Hannah could probably get her hands on one for some on scene analysis as good enough until there's full lab tests.