It's off centre but it doesn't look like you hit the threads, which is good. A little heat, lube and small square ez-outs works the best. If not, drilling out the head to the bolt dia as mentioned before will allow you to get the mount off and maybe leave something to grab on to. If you don't feel comfortable play it safe, leave it for someone else.
If your drilling a hole for an extractor use left hand drill bit, some times the screw will release in that process.
This actually makes a lot of sense but I am tapping out, it’s going to have to be the pro route before I do something worse than I’ve already done!
Smart move, let us know how it works out in the end!