This seems like a really big misjudgement by Kemi.
People do sometimes change - and he does seem to be trying to make up for his past - but in our polarised current political culture, with so much intolerance (especially on the Left, admittedly) no party should be seen to condone or accept any kind of violence.
I was likewise utterly shocked that Shahid Butt was permitted to stand as a Councillor (as an independent) despite his conviction for terror offences. More so since despite renouncing it, he still seemed to hold violence-adjacent views, eg about Israeli Maccabi fans. Thankfully he got few votes - but I don't think he should have been permitted to stand.
I do also feel disgust at the usual financial and sex- related revelations we've come to expect from MPs of all parties. In particular I judge Louise Haigh's fraud over her phone harshly as showing lack of personal integrity. And I also feel the same about Angela Rayner underpaying stamp duty.
But violent crimes - or inciting violence - especially related to only certain groups of people, or against people with specific political beliefs - are different. That's a line we must hold.