Does he get any benefit of Me having it added?
Discussion
No, he does not have any advantage other than that which any other relay operator (most of whom we don't even know) gets which is your connection data.
There is a 3rd option but it is often down including now (perhaps it's permanently down) so I didn't suggest it since you're on damus and adding too many relays on mobile really hampers battery life:
wss://nostr-us.coinfundit.com
At least with sf1 it's reliable and if it gets taken down I will know and can advise people. Resiliency is an important part of nostr so relying on mostr.pub alone is not a good idea. It would be nice if there were further relays writing to mostr but this will significantly increase the traffic and therefore the expense to run it (because so many more people will connect to it).