Those sites are probably a scam. I'd setup my own botnet if I wanted to rig any contest like this. Keysight didn't even use a captcha.
Honestly I think scope month in general was a fraud. IIRC we had one person "win" on the eevblog. That person complained about paying taxes and in the end rejected the scope. Also funny how he registered on the forum the day he won, claimed the contest was marketing BS, and then deleted his posts. Sounds like a conspiracy to me.
If Keysight really sends scopes, and if the "winners" even exist, then there's really not much you can do about illegitimate voting schemes.
Honestly though, even if you did not have the eevblog army, you should win because the other videos are abysmal. Most don't even have a lab worth $200 and claim that they need the 6000x? Wtf?