We are obviously going to disagree about this. I think it's entirely relevant. The same argument applies. He felt it was 'essential travel' even though the police urged him to comply with the restrictions. It has to be the same rule for everyone or anyone could say that they were travelling the equivalent of Wales to London to visit relatives just to deliver essential supplies. He is an MP, voted for by the majority of his constituents, and representing them and their interests. If Cummings should be penalised for his trip to Barnard Castle then Kinnock should be punished for making his trip to see his parents, coincidentally on his Dad's birthday, of course.
On the basis that they broke the rules - yes it is the same. We can argue til the cows come home which is a worse breach, but that isn't the point - they both broke the rule and should receive criticism and potentially warnings or action from the police.
But that isn't the only matter - as Cummins is one of the chief architects (actually almost certainly the chief architect) of the policy then his breach is more serious. Firstly from the perspective of hypocrisy and 'one rule for us, another for them' - but also his breach is far, far more serious in terms of bring the policy itself into disrepute - it is far more corrosive for public confidence in a policy if the person who wrote that policy can't be bothered to abide by it than for someone who had no involvement in the development of the policy.
So, yes the police response should be the same (and indeed the Durham police have been at pains to state that are treated this incident exactly as they would for anyone else) but the response of the public is, quite rightly, different, and the response of the government needs to be different too if they are to rebuild trust in the policy.
If you want much closer examples, then you need to look at Ferguson and Calderwood, although their involvement in policy development was less than Cummings and their breaches were less serious as there was no evidence than anyone involved had symptoms, and was likely contagious, unlike for Cummins and Wakefield. Yet both of them resigned. I guess neither was as valuable to Boris as Cummings.