It was an SPFL game ordered game postponement on the back of nasty Nick's statement that she didn't expect to see Celtic playing for the next week. This was purely to appease the Scottish Government as they were contemplating putting a stop to football again until we are further through the process of coming out of lockdown.
It had nothing to do with any requirement to self isolate and nothing to do with UEFA - it was, however, convenient that the suggested period for suspension of their games ended just before their European tie.
Their players, apart from Bolingoli, do not need to self isolate and have continued to train. As such it's unlikely to be of any interest to UEFA other than noting the fact that one player, who has tested negative, is isolating in accordance with Government requirements re travel.
So they will be unlikely, I would think, to be thrown out of Europe.
We will just have to settle for the points deduction