"You can develop on Z80 if you want to, that does not make Linus's argument any less valid. Tere's simply no rational reasons to run ARM servers."
This is completely backwards.
If we can get ARM servers that don't have invisible privileged cores that cannot be monitored or validated, it may become possible to run on machines that we can trust. The hidden service processors in Intel chips means you can never be sure your hardware is not compromised.
Moving to servers that are the hardware equivalent of 'open source' where everything can be inspected and validated is something far more likely on an ARM implementation than Intel.