Well to conclude, having bought more cobalt bits i drilled it out further and the remaining sleeve of the bolt became visibly loose, so i was able to fold it in on itself with a tiny chisel and then pull it out with long nose pliers, kind of like those videos on youtube of massive ear wax removal lol. What was left on the hub wasnt great, so i retapped it and put the wheel back on and it torqued up to 140nm without issue so ill accept it and keep checking its torque (when it actually gets taxed and back on the road).
Its an old vehicle and will be used for many more years hopefully so rear bearing renewals are inevitable and will get replaced in due course anyway.
god i love cobalt bits so satisfying to use. Wish i knew about them before recent times
What BMW, I ran a BMW specialist for 40 years, still have a stash of mainly smaller parts, i.e. no body panels, except E23 front wings and fuel tanks! don't ask.....................