Insider trade on Splunk acquisition?

I don't know if this is genuinely suspicious or not. Is buying 20K of options an unusual thing? Or is this something that happens regularly with options expiring worthless or with a small gain - and it just happened to hit big this time?

IE "someone bought a lottery ticket and won" - interesting to know if they play the lottery every other day (and don't usually win?)

It's definitely suspicious and will probably be looked into. If it turns out it's a trader who regularly buys soon-to-be-expiring option calls, maybe it'll fly. But if the trade was made by someone who doesn't regularly make $20,000 options bets, they will need a good explanation.

Why will they need a good explanation? Can't they just say I lucked out and the burden of proving insider trading would fall on the SEC? Innocent until proven guilty right?