Assuming they got permission to overfly Canadian airspace, BDL is only 61 miles further from DTW than EWR is. Even if they'd gotten all the way to EWR, it's only 116 miles. I commonly see UA flights from IAH (140 miles) and AA flights from DFW (190 miles) diverted to AUS.

In inclement weather, alternate airports are selected in advance. It would be a severe breach of safety protocol for a flight to be dispatched without enough fuel to reach its alternate airport. The FAA requires that flights carry a 30-minute cushion of fuel when operating in good weather (VFR) and a 45-minute cushion in inclement weather (IFR) -- and if the weather's bad enough, and the target airport doesn't have an instrument approach procedure in place that would allow for a landing in the current conditions, it's actually destination + distance to alternate + 45 minutes.

Allegiant made the news for declaring a fuel emergency in 2015. It's not something that happens very often, thankfully. :-)