TWitter usually takes a while to do anything about anything. Do you realize how many reports they get a day? They usually focus their efforts on high profile accounts first and get to others whenever they get to them. Most people didn't see those, Most people,however, do see the presidents. Until someone makes some other bad post go viral, it is a non issue.And so they should with others too but apparently it's perfectly fine for a load of Chinese bot accounts to try and spread the claim that Coronovirus was started in the USA. Hell it was only when 4chan started hacking the account that Twitter bothered trying to actually do anything about the ISIS recruiters.
Hell some of trump's retweets that got pulled were a non issue until he made them viral.