I'll link you to one of many of the examples of the line of attack he's been using for some time:
https://twitter.com/keir_starmer/sta...70538075578368
As you say, it's usually in the context of attacking the PM's lack of these qualities, but the unavoidable implication is that Starmer lays claim to these principles himself, which in my opinion he has no particular right to do, given the political games he has played to get where he wanted to be. You might disagree, which is fair enough.
Are you a lawyer or are you just taking offence on behalf of others in that fine liberal/left-wing tradition? I should think most lawyers are wealthy and thick-skinned enough not to be offended by mildly tongue-in-cheek asides on the Notts County MAD Messageboard. Let’s just say lawyers are well-trained in constructing a case to present their clients in a best light that may not be entirely accurate.