A cycling site with 275k MAU would be in the very lowest category where compliance is things like 'having a content moderation function to review and assess suspected illegal content'. So having a report button.
Im surprised they don’t already have some form of report/flag button.
Also if it is well monitored and seems to have a positive community, I don't see the major risk to shut down. Seems more shutting down out of frustration against a law that, while silly on it's face, doesn't really impact this provider.
From another commenter:
Platforms failing this duty would be liable to fines of up to £18 million or 10% of their annual turnover, whichever is higher.