Some Ardent 2.4 tires on a set of P-35s or Gordos would give you some added float on soft surfaces albeit not as much as a fat bike.
That's what I said.

My bottom bracket lasted 3 months...
By that time I had 300 off-road miles on it. It got wet and dirty A LOT.

what pressures were you running? the only flats I've seen guys get were from sidewall slits or pinch flats 'cuz there wasn't enough pressure. run the correct pressure for the terrain and you should be fine. but, all bikes flat - not just fatties.
About 7-8psi in the snow or sand. 10-12psi in the summer time when the weather was fine. No pinch flats, just picking up thorns and thangs.

which consequently results in a less than 1 mile walk back to the parking lot at any of our trail systems. the longest being ScoCoPa, which at anytime you're right near the road so you can basically coast back to the trailhead.
Yes which is fine if you only ride in the QC. Go to Missouri, Wisconsin, Minnesota etc where you can easily get 10 miles from the trailhead and it can become a big issue. Once you've gone through your spares, you have to find the nearest fire road or forest service road and make your way back to the trailhead.

gotta pay to play.
Can't argue with that! We said the same thing in our drag racing days.

horses for courses. there's no One-Bike-to-Rule-Them-All, but for gigantic's needs I believe the fat bike is gonna bring him greater joy over the other option.
I believe the 29er will bring him greater joy than a fat bike, so there! :-P In all seriousness, I'm sure he will enjoy the fat bike immensely.

FWIW I accumulated over 600 miles off-road riding on my Mukluk in Iowa, Missouri, and Wisconsin. I didn't get to ride Minnesota until after I got the 29er.