You forgot to close the loop: the HARRP array has a nasty side effect. It causes disruptions in space-time, ripples that actually go backwards in time, and one of these disruptions caused the Tunguska event.
There. All nice and neat. And if you doubt it, you’re one of THEM.
What makes you think YOU aren’t one of Them, to begin with?
Is it a bluff? Or a double bluff? Or even a TRIPLE bluff?