If it ends up on eBay, I do not think Keysight will send giveaways to Dave anymore.
If the scope was to end up on eBay it would mean the person who was lucky enough to win the scope didn't really want it so they should not have entered the contest in the first place. Any winner who puts the scope on eBay could find they get a big backlash from other Forum users as their Forum user ID will be announced when the winner is selected.
If the competition had a choice of two prizes. Which the winner(s), can choose between, after wining.
(1)...The scope, as currently offered.
(2)...The equivalent $/£ value of the scope, to spend on a wide range of test equipment, available on keysights, website for your country. Signal generators, power supplies, decent scopes, meters, etc etc.
Massively improving many peoples workbenches.
I bet, at least one entrant would go for option (2).
I probably would, especially if getting the stuff in the UK, meant I had NO tax duties/VAT to pay, etc.
tl;dr
If they sold the scope on ebay, then spent ALL the money on getting a decent, all round, set of test gear and tools/components for their home lab. Some would not consider that too unreasonable.