User blog comment:Xilinoc/Ch. 557 - He Already Set His Life Aside/I Already Threw Away My Life/@comment-1387259-20131113144349/@comment-28861328-20131113165749

Temporarily just means that, at some point, it will end. That could be after the battle, or it could be at the end of his natural life-span. Obviously it doesn't seem to be too concerning, as his great-great grandfather has a great deal of knowledge about it, and has seen others use it, and he seems to be very much alive and well in his dog form.

You can't argue that he "just hasn't used it yet", because that would present the same issues of his heart being ripped out. Stream also tends to spice things up, so it'd be best for the translators to fix it.