Controlling mother bf

So my boyfriends mom wants my boyfriend to have a tracking device on his phone at all time , her thing is it’s for emergency only and she can see where he is , how fast he’s driving and all sorts of other things I feel like it’s a breach in his privacy and mine he’s 22 years old and I just don’t know what to do I feel violation and feel like his mom is being controlling she threatens to cut his phone bill and he says he wants to be on his own plan expect she won’t allow it. I don’t know how to help him and how’s it’s gonna effect my relationship with him , his parents treat him like a child and I’m sick of it , and he’s also upset but he can’t ever stand up to them. What should I do? Should I leave ? I am so lost and upset I need help :’(