No, it won't get into the pump because the pump has a check valve to prevent reverse flow. And that is a great point. You should disconnect the hand tightened connector on the suction side (left side) of the water pump, and let any water drain out. Or disconnect both side, prior to doing the antifreeze. Would not hurt to run the pump for a few seconds while that line is disconnected. Then reconnect and do your antifreeze.
I'm trying to put pink stuff into my Sunseeker now. I can see why FR just wants you to put it into the tank, because that way is foolproof. But I refuse to do that, I've never had to do it, and I don't want to deal with the remnants of antifreeze in the tank. My last mini MH came with it in the tank, and I never got it out until I physically removed the tank from the rig and rinsed it out. Never again.
But I've never had a rig where the pump sits at the low point like this one. You cannot winterize the pump without either disconnecting the line(s) and running it to clear it out, or else letting it pump some antifreeze through the system. The same caution applies to using air to blow out your lines. If you don't take care of the pump separately, water will collect there.
2014 Sunseeker 2300 Chevy