I'd think this is a bug in the VM OS if this causes such increased CPU load like you describe in your linked post from a few months ago.What about the "Remove all USB controller from VM" ?
I checked PVE8, still hardcoded:
See this old post:
But anyhow, it might make sense to add an option which allows one to disable USB support completely for a VM.
Feel free to open an enhancement request over at our Bugzilla instance: https://bugzilla.proxmox.com/ so that we can keep track of this.