This all seems a bit silly, and could easily be attributed to a communication issue.
On CrowdStrike's end, it's much more likely that their systems changed a few heuristics so now it flags certain msiexecs as malicious. Most anti-virus type software are highly nondeterministic in the way they operate, with tiny changes in detection engines able to cause large changes in the way some threats are detected.
Even modzero themselves admitted that the vulnerability is not of great severity so the motivation for the security triage team to put more resources in validating a non-severe bug are probably very low. They likely just tried to run the exploit, and didn't think much of it after it didn't work.
Also if modzero is not participating in a bug bounty program then CrowdStrike has no obligation in providing them with free trials or such in verifying a vulnerability fix.
I'm no fan of CrowdStrike (in fact, one of the more memorable moments for me at my previous job was my boss calling them "ClownStrike"), but it seems as if this is just a bit of overzealous entitlement from modzero as well as not enough testing on CrowdStrike's end.