Negative.
Here's the issue with your statement.
Its actually NOT that simple.
My parents are in Florida for the winter. If there is an emergency (which has already happened last year) they need to be able to contact me.
So when my phone is on DND they can call thru anytime. If I put my phone on mute they will NOT be able to contact me.
Imagine how may people have loved ones looking after elderly or have partners working high risk jobs. Your phone could be a lifeline to these people.
Muting your phone is not an option for thousands of Canadians, me included.
Also the system is used for more than just amber alerts.