My 2 cents: I started training BJJ as my only exercise before training strength, and I got nasty injuries, including hurting my ACL badly and a herniated disc in my lower back. I had zero ego in the gym, tapped early, but when we're a white belt training with other white belts, we just don't know how to do it. Also, all injuries happened towards the end of the session, where I was already gassed out and my decisions were not as sharp as in the beginning of the day.
I believe that it should be much safer to a person who have been working on their strength and endurance for a long time. Be extra careful!