yes well, it isn't a permanent increase in power, the SB energy flowed around him in a yellow ball and he was mega pissed while doing it. He was gritting his teeth the entire time, the strain on his body was probably overwhelming.
Also I'm pretty sure from the japanese translation of it that he didn't know he was absorbing the SB energy until he was already done with it. The SB just sort of got sucked into him when he powered up.
And Krillin says something to the matter of...... A Genki Dama?(Spirit Bomb), I thought only when Goku's heart was calm was when he could do that."
And then he faints or something. I dunno, he gets his ass beat in every movie, he even admits it in Brolly's Revenge in the end(japanese version). He says, why do I get beat up every time???