Unauthorized installation of DirecTV dish on apartment roof

I am the owner of a 50 unit apartment building in West Los Angeles. I discovered just recently that AT&T DirecTV ignored and violated my alarmed roof access door and proceeded to walk on my flat roof and then installed one of their dishes at the request of my tenant, without contacting property management or me the owner. When I called AT&T’s office of the president they informed me that their policies are responsive to tenant requests and that they have no obligation to get the permission of the property owner or management. This is preposterous. Our roof has no guardrailing and therefore is it dangerous to walk on and is in violation of OSHA laws to work on without proper safety precautions (https://www.osha.gov/Publications/OSHA3755.pdf ), yet I am aware of no precautions taken by AT&T DirecTV to protect their workers. Further, a worker walking on a large flat roof like ours can step on nails or other debris and pierce the waterproofing membrane and cause water to leak into our top floor apartments. AT&T DirecTV has indicted to me that this is not their concern.

AT&T's own forum indicates that their satellite dishes cannot be installed on apartment building roofs:
https://forums.att.com/t5/DIRECTV-Installatio ... ns/td-p/4706798