>You do not need to abide by UK laws, even if your website is accessible from there.
The UK government does not agree.
All they can legally do is bitch and moan and order UK ISPs to block. There's no action they can legally take against Imgur.
Why shouldn’t Russia be allowed to exert their laws extraterritorially? Or Mali? Or Sudan? Or the Iranians? Or China? Or Israel?
What you’re asking for is the end of the internet, full stop.
It's likely simpler to just block access to the country's IP ranges (or ignore!) and move on.