I have a question which the report doesn't clarify.

What type of airspace was the glider and bizjet flying
in at the time?

Controlled or VFR?

Almost certainly IFR as they were descending from positive
control altitudes. It's rare (but not unheard) for bizjets
to not be operating IFR.

I'm sure you speak only of the BizJet.. the glider was VFR and not under ATC
control and not required to be under ATC control.

BT