It's ebay, not Christie's Auction. If that's what the seller wanted, they got it. When they put it on ebay they were to expect whatever outcome they got, it's a CONTRACT.
Now it probably doesn't matter where it goes after that, you own it, you have that right. I can only hope that it will be ridden and appreciated, but again, I have no say.
So it doesn't matter now, it was a FAIR transaction and I would gather the sale was completed, no?
It sounds like the seller wanted Grandpa's bike to be of use to somebody and it wasn't to them. Lucky, yes. Probably altruistic, I suppose. Not everyone thinks of old bikes as a cash machine. Sorry, I respect your business sense but I've also had a lot of fun since I bought a Rollfast middleweight from the late 50s for $50 on ebay in 2008 and named her TEMPEST.