Wearing an N95 (or higher) mask should be absolutely fine, particularly if it has a valve (which makes it easier to breathe out).
On flights dating back to January/February 2020 I was on numerous long-haul flights where [almost] everyone was wearing masks (surgical, N95 up to P100) for the duration of the flight (with exception of meal & drink intake), as well as at the airports.

That above article is a bit ridiculous, and I wouldn't worry about it. Besides, how could they possibly know he didn't just fall asleep behind the wheel as has been a common occurrence since the invention of the motor vehicle!

Flying with UA whilst wearing a mask should cause no serious issues, although a slight discomfort may set in, especially if one isn't used to wearing a mask for prolonged periods of time.


A pic showing 50%+ already wearing masks at HKG on February 1st: