The keys are twofold. First is the definition of "transfer" to include any "intent to deliver" to another person, even in the very short term. The clause specifically notes that it includes but is not limited to gifts and loans of any period. The second is a quick ramp-up into felony territory.
To point out an extreme and arguably silly but from my reading unfortunately legitimate example, it looks like you would technically commit a felony by handing your firearm to your firearms-legal friend to hold while you're, say, pouring some water, and then taking it back. You would certainly do so by handing it to a friend to fix (say, unjamming it) and then taking it back.
In both cases, the first transfer would be a misdemeanour, the second a Class C felony. And that's crazytalk. "Here, hold this" shouldn't generally lead to a felony violation. What bothers me is that the authors seemed to be somewhat aware of that fact - they make an exception for repairs by gunsmiths, but only Federally-licesnsed ones. Which most aren't.
So even if you're for gun control in general... this is just bad law. If you're reflexively voting yes, please reconsider.