Because that's the only way Apple allows apps to stay open in the background on iOS so your SSH connection doesn't disconnect after 10 minutes. And the Mac app is a universal app with iPhone/iPad so it has the same permissions. If you never enable the "Connection Keeper" feature it never requests the permission.
A lot of photo sync apps also have to use this workaround to be able to sync your photos in the background, it's been a long-standing issue with Apple's platform.
And App Store rules means they have to justify the location permissions so they add a totally unrelated "make a log of your location throughout the day!" feature in the app just to get App Review to approve it, even though everyone knows that's not actually why they need it.