You can't answer why Rayner's attendance makes any difference because you know it doesn't. The meeting wasn't illegal.
Everything else is just attempts to distract from the 8(?) social events Johnson attended breaching draconian legislation we had to suffer, the pretence of fury about the non parties (all guidelines were followed, "I share your fury"), the desperate sacking of Allegra Stratton, being dragged in to appointing Simon Case to review and then discovering that he had attended a party, more lies to Parliament and crucial ongoing failure to correct the record, the slur against Starmer, appointing Sue Gray and then at the point she was ready to finalise then getting the police involved and the faux smirking apologises.
And in the background the fast tracked friends and family covid contracts, the lost phones, the protective ring around care homes, Hancocks face, hands and no space employment of his mistress, the attempts to subvert Paterson's clear wrong doings, the Russian report and close relationships with dodgy donors and on and on.
The Conservatives - under Johnson - have lost sight of the "moral high ground".