It makes sense that you want users to customize to add more monitoring but I think there is a middle ground to allow minimum viable notification rules. This would allow customization to an extent if the policy is enabled to allow people to make it more but not less aggressive. I agree that a phone is personal and do not have work email on my phone because I am unwilling to give remote wipe to IT. There is a very big difference between hey I want you to answer your on call pages that you have agreed to do during after hours and saying that I need complete control of your phone.
I think like most features are great in the hands of sane people and a complete disaster in the wrong hands. I think we can find a middle ground to enable both sides.
If you don’t like you teams/companies stance there are plenty of fish in the sea.
I do require all my on-call engineers to have push or phone notifications set up within a certain time frame as their roles require them to respond to an incident and not just sleep through it. In my career I have seen this happen a few times: had an engineer who thought email only notifications was appropriate and after a system was down for a while it escalated to another team member pulling them out of bed. I view having a minimum notification policy is a protection for not only the company but the members on the team. I spoke with the engineer after and told him he could specify something more appropriate if not I would choose extreme notification rules for him. Needless to say you can solve it in this manner but it can cost you a lot of money to learn the hard way.
If your engineers are being woken up in the middle of the night often this is not something pagerduty should solve for you and probably requires application, infrastructure, and/or monitoring changes.