As much as I think the Keira beer should be investigated just for transparency.
I would be very surprised if KS did something against the law.
As much as I have been disappointed in his ability to turn the Labour party around I've always felt he takes his duties towards the law as a lawyer seriously.
Imo Boris knew cake gate and the garden parties which were labelled as parties were against the law at worst and against the spirit of the guidance at best.
Imo KS would believe his actions were within the law and the spirit of the guidance.
I just hope the investigation is fair knowing that if he's fined he's very likely morally going to have to resign and will.