What he said was, a couple of weeks of QA, per stack, per hardware enablement.
Given that new hardware is constantly being released every couple of months, that adds up to a lot of QA. And as they said in a followup, that's "a couple of weeks" for a team of people and not just one or two.
So yeah, "two (additional) weeks of QA" wouldn't be that bad, but really it's more like "two (additional) weeks of QA, multiple times a year, for a team of multiple people". And that's not insubstantial given the meager revenue opportunities in the desktop linux market.
The tl;dr is that the comment on one engineer's tasks and the QA that one of the chores takes weren't intended to communicate that the team was 1 person big (or, presumably, that there's only one QA chore).
FWIW, my read of the wording around QA was that when a each new hardware platform is enabled, it takes 2 weeks for the whole team to work through their test cases. I assume, though I don't know, there's a lot of other QA done, such as when a new feature is added or something.