OK, but
NBC Sports Philadelphia IS available on Verizon FiOS, RCN and Service Electric, plus Hulu with Live TV and PS Vue. So it's not like Comcast is withholding it from their competitors in general. Maybe D* just didn't want to pay whatever Comcast was asking to carry it.
Unlike AT&T with the decision announced today, Comcast actually did have a number of "behavioral conditions" placed on their merger with NBCUniversal. I'm pretty sure those conditions would have kept Comcast from being able to do what you're saying happened with Philly Sports. (That said, I'm pretty sure all those behavioral conditions recently expired or will soon, as they were only in force for so many years after the merger went through...)
So while you complain that other companies get away with stuff that AT&T doesn't, today's ruling is actually the opposite situation. The most comparable merger to AT&T + Time Warner is Comcast + NBCUniversal. And in that deal, a number of conditions were placed on the company to try to keep them from harming competition and consumers. But NO conditions at all are being placed on AT&T.