Well it is totally understandable that it is moving now.... back in 2017 when we had the previous all-time-high price, things was still a little "hot" for the hackers to move those coins... so they most probably thought they would wait until the dust settled and then they would start selling the coins when the spotlight are not on them.
The latest spike in the price must have been the trigger for their decision to move those coins... or they did a bit more research into what methods would be safe to move those coins. (Testing different Mixer services with criminal activities to see which of them are reporting to the law enforcement agencies)
I hope they make some mistakes and that they would get caught!
I don't really think that these coins will ever stop being "hot". With all the automated tools to follow every large transaction and coins that are linked to hacks, it will trigger warnings instantly.