It's a no-brainer for those who know what they're doing to do some mixing before transferring it over to an exchange, but my golly I can't believe that some of them actually had the guts to do a YOLO and send directly to an exchange without mixing first. Though of course, there's a possibility of stolen identity but still, the exchanges should have been alerted of those coins coming in on their platform to at least freeze the coins and check who is behind the possible transaction and be the hero of the day.
I wouldn't be surprised also if we see another round of posts/articles accusing mixers/coinjoin services of aiding money laundering.
This is not new considering that all they do is just mix coins and make it untraceable, regardless of whether the coins they receive are tainted or not. This is the main reason why governments are having their eyes peeled on mixers and regulators keen on passing some regulations against this kind of service as they see it as a form of money laundering tool that is easily accessible.
I believe Chipmixer, being centralized, is also capable of blocking those btc's if they wanted to but that would put a huge dent on their reputation.
Pretty sure ChipMixer will hold their ground. They're in hot water for similar things for years now but they remain operational and still going strong amid all these scare and whatnot.