I thought this was a very mild, even gentle depiction of Whovians.
Oh it was, but...Reddit's gonna Reddit, and the internet's gonna internet.
In terms of the “American” accents, I’m not a native English speaker, so a lot of that detail goes by me unnoticed.
Honestly, it's not even the accent. I think the guy's accent was...adequate (full disclosure, I'm Canadian, so I can't judge US accents too harshly). But the dialogue often seems just a little stilted to me, with word choices that don't quite seem to align with what an American would say.
The most egregious DW example to me is from way back in "The Poison Sky"/"The Sontaran Strategem", when the ostensibly American Luke Rattigan kept ranting about how "clever" he was, which is simply not something an American (or Canadian, for that matter) would say. Nothing in this episode rose to that level, but it just seemed a little off.
I mean, is it any COINCIDENCE that this episode was set in FLORIDA?