Actually in 9.5 a tenant admin can create and execute any backup they want; this being said, I've received this request already 3 times from other providers. To better understand the request, would a "restore only" user do what you need? You also say he should be able to run a backup created by others, who's this role? A higher user from the tenant or the service provider?
EMEA Cloud Architect @ Veeam Software
Veeam VMCE #1