I mean imagine if the War got canceled for like 10 years and the space marines got to bro it up with humans rebuilding civilization. Even Fabius Bile sneaks back into the Imperium with a giant fake mustache and opens up a shop where he sells extra cute genetically modified Cats and Guilliman orders a gryphon from him saying comically you look familiar... Of course the highlords know Bile is back and look the other way because he shares his research with them.
Trayzn opens up his Musuem to the public and the Harlequins put on circus shows for humans.