congrats on making the move to bike commuting!

At 6'4/290, I would not say you need to be terribly worried about the strength of the frame; just stay away from high-end supercarbon. Fortunately poverty is your friend, usually cheaper means heavier means stronger.

You do want to make sure you have robust wheels, which mostly means high(er) spoke count. You want at least 32 spokes front and rear, it might be advisable to bump up to 36 in the rear, where more weight goes.

But at 2.5mi each way, that is quite a short commute, and you don't need much of a bike to get that done, so good news you can do well with not much $$.

I'm counting 36 spokes both front and rear on that breezer, if that is within your budget and you like it and you get one that fits, it will work very well for you; even better than you need, which just means you'll also be able to take it out for longer (enjoyable) recreational rides.

However, since you are a man (at 6'4 290 I assume you are!), I would recommend to you instead the downtown EX, rather than the "EX-ST" (stepthrough), but really only "fashion" grounds, since stepthrough frames are usually for women. Although they can be useful also if you plan to ride in street/dress clothes rather than shorts/tshirt and shower/change at work(school). Depends on what facilities you have available.

I took a peek at diamondback insight, that would do you well too, give you more of an athletic vibe than a professorial vibe, which you might prefer since you are a former college athlete.