The problem is they will need to employ a localization team for Portuguese full time and this will cost them a lot of money, they need to weigh the cost of translating all game text for the lifetime of the game against the extra money they would receive if they would get less money than it would cost, it wouldn't be sustainable.

Unfortunately this is the reason, and with SE's current position, I don't think they could take any cost if Portuguese localisation didn't make a profit.