This may not be just PR. EA is a large company. As a result, they are naturally going to have a more diverse workforce. If I had to guess, there are LGBT workers at EA.
The diverse members of the workforce are naturally going to want to work on projects that interest them. And will naturally have more insight to bring to those projects.
Additionally, LGBT is a dramatically under-served market in video gaming (indeed, most instances of LGBT representation come from EA studios such as Bioware and Maxis). There is always money to be made in catering to under-served demographics.
Few things are entirely altruistic. But this is mutually beneficial news and should be welcome.