I suspect it's lazy reporting on the BBC's part. Mask-wearing has been the trigger point for so long in the west that's it's the default explanation. Whereas in China, the trigger point is still assembly (which is where the west was 2 years ago).
What Chinese leadership knows is that masks are nigh-on worthless for Omicron (I've seen numbers as low as 30% efficacy for N95 and basically no efficacy for cloth and surgical vs omicron) and that the only way to control it (without high prior infection rates and/or better vaccines - neither of which they have) is physical separation.
Another issue is that Omicron isn't actually much less severe than previous strains on its own - it's just that in most areas there are effective vaccines and basically everyone has gotten covid before, so it's effectively less severe. But at the same time, it's way more transmissible than previous variants (like ~10x so). So China's put itself in a bad situation. If it lets loose, Covid goes wild and their healthcare system is crushed because there's basically no immunity against the world's most transmissible virus. Everyone will get it pretty much at the exact same time and 10-20m people will die with little to no healthcare within the span of a month or so. Or they keep locking down in perpetuity until something changes (they get a better vaccine? they do a controlled burn? the virus gets a lot weaker? revolution?).
Why would they be cutting the up-close footage of people in the crowds not wearing masks if it was just about assembly?
You can still see that crowds are not being spaced out from normal angles of the match, they would still know that restrictions aren't in place for those abroad.
What Chinese leadership knows is that masks are nigh-on worthless for Omicron (I've seen numbers as low as 30% efficacy for N95 and basically no efficacy for cloth and surgical vs omicron) and that the only way to control it (without high prior infection rates and/or better vaccines - neither of which they have) is physical separation.
Another issue is that Omicron isn't actually much less severe than previous strains on its own - it's just that in most areas there are effective vaccines and basically everyone has gotten covid before, so it's effectively less severe. But at the same time, it's way more transmissible than previous variants (like ~10x so). So China's put itself in a bad situation. If it lets loose, Covid goes wild and their healthcare system is crushed because there's basically no immunity against the world's most transmissible virus. Everyone will get it pretty much at the exact same time and 10-20m people will die with little to no healthcare within the span of a month or so. Or they keep locking down in perpetuity until something changes (they get a better vaccine? they do a controlled burn? the virus gets a lot weaker? revolution?).