I think you're right. A BIX probably doesn't have much flow restriction, at 2 gpm.
You know what's funny? My pump would push 2.5 gpm through that rad...
Another thing to consider: the pump wouldn't be anywhere near it's efficient range: it's going to suck up a lot of power, to achieve that 2 gpm.
You might be right about the pressure, for the pump intake side.
My pump collapses 1/2 inch thin walled tubing (in a circulating loop) so I switched to 3/4 braided. No test run yet, but I'm confident.
If you're really worried, then you might invest in a flow sensor (not a flow meter) just to check that there is some (any) kind of flow. Wire it to the PSU(s), for a complete system shutdown. Easy.