practically speaking
a) it will crack before it breaks so you could just keep an eye on it and
b) it might be useless now anyway, in that I'm not sure you could bolt anything to that boss now; most things come up flush against the frame.
The damage is so severe that I would expect the powder coat to have shown signs of strain locally if the damage had occurred post-coating. Thus is it possible that the frame was damaged before it was coated?
Regarding repair options. CrMo can either soften or become ridiculously brittle when heated for brazing, depending on the thermal cycle. I'm guessing at the former, else it wouldn't have deformed like that.
It may be possible to pull the worst of the damage out (eg using a slide hammer) but then again such treatment may just pull the boss clean off the tube.
One way of helping the repair along would be to drill and tap the M5 thread all the way through one boss and then to use a long M5 bolt to apply load against the other boss region (which is relatively solid). This could maybe be used in combination with a slide hammer or other puller of some kind.
What a pain! If you want to be perfectly confident in the bike probably a new frame is the best option.
cheers