Ok if it is not bad what is your gut reaction to this:
"Hey Dad, it is me, your son. I got a message that you are watching porn right now, please stop sinning!"
Also do you really think it was his son's idea to do this, that this was an actual mutual decision where the power difference between an authoritarian father and a son compared with threats of going to hell did not hinder him to say "I don't want this."?
If two adults decide to help each other this way fine, but this is solely to shame the son and to control him and to have control over his sexuality, but what it actually does is making porn "the forbidden fruit" AND most likely has the son either circumventing the software or having a second device or watching porn together with his best friend, who has a not controlled phone, jerking off together. Not that that would be bad.
Overly controlling parents do only one thing: Raising children that are good at hiding and lying and probably will feel guilty their whole lives, for completely normal feelings and normal things they do. It is messed up and even more messed up to involve your children into you own shortcomings, if the father really needs his porn addiction monitored.