From the Snowden revelations themselves, the probability that that website is on a watchlish is basically 1, meaning they're aware of your existence and intentions before you even click upload.
This might seem outrageous but that's the mindset of militaries and intelligence agencies in every country. If they have a chance to learn about a potential threat they will instinctively take it and it wouldn't be even slightly controversial. Snowden's revelations only confirmed that, they'll take everything they can, hide whatever they can and debate its legality later.
Second, Snowden tried to use official channels, but that failed and he wasn't so stupid to let them cut him off before he could pursue others.
But third, you'd fault him for not using technologies that either didn't exist or weren't effective at the time and ignore the fact that they only became so precisely because he revealed what he did? Seriously?
The man who understood and maintained these surveillance systems better than almost anyone decided he couldn't trust anything but extreme precautions employed by an expert against the technology of a decade ago, let alone today. As above, Intel agencies aren't truely accountable, are ridiculously capable and will never accept the situation of being stumped by obvious threats because they use Signal and Tor. If they need a how-to website they've already lost.
This might seem outrageous but that's the mindset of militaries and intelligence agencies in every country. If they have a chance to learn about a potential threat they will instinctively take it and it wouldn't be even slightly controversial. Snowden's revelations only confirmed that, they'll take everything they can, hide whatever they can and debate its legality later.