Microsoft didn't write the Falcon sensor software nor did they put it in the kernel. In fact, Microsoft has been shouting to the heavens trying to shift the blame from CrowdStrike onto the European Commission, because they want people to irrationally hate antitrust so they can turn Windows into shitty iOS and monopolize the security market (and applications market) for it.
Furthermore, Microsoft does actually have some rules regarding what you can and can't put into a signed kernel driver. Specifically, they won't sign kernel code unless they've seen and tested it first. CrowdStrike deliberately circumvented this rule by implementing their own configuration format - really, just a fancy way of loading code into the kernel that Microsoft doesn't have signing control over.
If there is blame to be had here for Microsoft, maybe it's that their kernel code signing program doesn't scrutinize third-party configuration formats hard enough. I mean, if you sign a code loader, you're really signing all possible programs, making code signing irrelevant. And configuration is more often than not, code in a trenchcoat. It's often Turing-complete, and almost certainly more complicated than the actual programming languages used to write the compiled code being signed off on.
But at the same time I imagine Microsoft tried this and got pushback. That might be why they feel (incorrectly) like they can blame the EU for this. Every third-party security solution does absolutely unspeakable things in kernel space that no one with actual computer science training would sign off on, using configuration to wrestle signing control away from Microsoft. Remember: Crowdstrike is designed to backdoor Windows systems so that their owners know if an attack has succeeded, not to make them more secure from attacks in the first place. Corporations are states[0], and states fundamentally suffer from poor legibility: they own and operate far too much stuff for a tribe[1] of humans to meaningfully control or remember.
The problem is that we have two different entities that all have the ability to stop this madness. When states run into this situation, they impose "joint and several liability", which means "I don't care how we precisely assign blame, I'm just going to say you all caused it and move on". In other words, it's Microsoft's fault and it's CrowdStrike's fault.
[0] ancaps fite me
[1] Maximally connected social graph with node degree below Dunbar's number.