Are you aware of the number of student visas that gets issued every year? Here's the number for the past couple of years:
2017 -
421,008; 2018 -
389,579; 2019 -
388,839; 2020 -
121,205; 2021 -
377,659
You're telling a CO who is highly familiar with the thousands of student visas that get's issued annually you needed 6 months to check out a flight training school before deciding on which one to apply to, while hoping they subsequently offer you an admission. A large majority of those with the student visas have never stepped foot in the US before applying for their student visas in the first place, and FYI - the tuition ranges between $40,000 to $60,000 annually for them also. While making a commitment "sight unseen" might not have been the right way to proceed in your opinion, the fact that you needed all of six months to check out potential schools didn't sound right to the CO too I'm guessing. The fact that you told the CO you ended up in Canada because of the work opportunity schooling there provides probably got the CO thinking you did not have the required fund to support yourself there either, which is why they have the concern about the possibility of you becoming a public charge in the US. I doubt using your 2 brothers in your home country as your sponsor will be accepted, the CO will wonder how come either of these brothers was not available to fully sponsor your flight school attendance which made being able to work a deciding factor. But now, they're able to sponsor you? I'm not trying to pile on you or needlessly call you out, just trying to explain how the CO might have perceived your application and what you told them which subsequently led to your being perceived as a potential public charge. Anyway, all of that is water under the bridge no, what's done is done.
If your friend's income is at or above 125% of the applicable
poverty guideline level to support his household and yourself combine together, yes he can sponsor you. His job does not matter, it is his annual income that matters.