Can it be argued that precedent against such cherry-picking was set in Bush v Gore? Yes, it was counties in Florida, however the principle is the same.
I don't think so. The Bush v Gore ruling addressed inconsistencies WITHIN the state of Florida. If the "cherry-picking" principle were extended to the rest of the country, then Jill Stein's petition to recount in Wisconsin would automatically force a recount in every other state. Since the Constitution specifically cedes the manner in which electors are selected to the individual States, I can't see that your argument would hold.
Talk about a "nuclear option"!
I think RC has a point. Only picking narrowly won red states to recount is exactly the same principle as the one in Bush vs Gore. If you recount all states with a margin of 5% or less in either direction it would be fair. What is happening now IS cherry picking.