Canary deployment for subset of Salesforce customers won't see much of revolt from customers compare to AV definition rollout (not software, but AV definition) in Cybersecurity where gaps between 0day and rollout means you're exposed.
If customers found out that some are getting roll out faster than the others, essentially splitting the group into 2, there will be a need for customer opt-in/opt-out.
If everyone is opting-out because of Friday, your Canary deployment becomes meaningless.
Any proof that other Cybersecurity vendors do Canary deployment for their AV definition? :)
PS: not to say that the company should test more internally...