Ah yes, that's a concern - but I have a job in Task Scheduler that re-writes my registry tweaks - mostly changing various tasks back to "disabled". You can trigger it hourly, or on an event. As soon as a selected event - such as a telemetry switch-on - hits the event log, the "disable" script runs.

There's other ways, like taking ownership of the executables and changing permissions to lock out the "SYSTEM" account.

And pihole blocks DNS resolution of the telemetry harvesters as well. Windows update won't touch that. It's not 100% effective, but I couldn't be bothered to take it further.