He would need to confirm that you have his permission on his instagram or something otherwise you may be accused/downvoted for plagiarism by the teams that check for that sort of thing.
Why not just send him a past SPC, see the winners, see the prizes :) See the rewards on Photography posts!
I will post photos not anywhere else online.
I have also sent him this link and will wait too see if he joins.
Another option would be to create an account for him (with his email and mobile number) and post for him from that account. Once he is convinced he can take over.
Suggestion for the next theme: friendship.