Ganon's pivot grab is definitely above average.
A few things to note:
Dthrow is okay. Sometimes I follow it up with a full hop Fair at mid %'s, which will sweetspot if it lands and will often kill because they don't expect it and they DI poorly. Also it's worth noting that Dthrow COMBOS into Dsmash at 0% on Snake. The Snake Killer Combo is courtesy of Z1GMA.
Honestly I haven't experimented much with Uthrow. Mainly because it only does 7%, as opposed to Fthrow's 13-14%. Even if you punish their landing with a Uair or whatever, it will generally do only 5-6% more than simply Fthrowing them. Which means that in order for Uthrow + punish to be better than Fthrow, you'd need to successfully punish their landing over 50% of the time after Uthrow. Which I'd imagine is unrealistic for most people. I mean, this math is obviously inaccurate, but the general idea stands.
I will always Bthrow if it gets them offstage. Ganon is simply too good at edgeguarding/disrupting recoveries to consider anything else. Especially when other throws will likely give up his stage control.