The article states, more or less, that the company is reallocating the aircraft to a market where it can make a profit during the Winter.
I'm sorry this one guy is inconvenienced. But airlines are not charities or not-for-profit organizations. It makes business sense to reallocate aircraft seasonally, and US (and others) have been doing that for years. For once, I'll agree with the Sand Castle and say 'good job' for maximizing revenue.
Lighten up, Pittsburgh. Sorry you got de-hubbed. In fact, I started with US in PIT many moons ago and wish it were still the US mecca it once was. I was there recently for business, and it was sad to see an empty US concourse in that beautiful airport.
But $ talks, and unfortunately, PIT doesn't generate enough of it.