I hate the style but have to accept this is the way young people express themselves & communicate (it takes me hours to text, putting in all the flippin' apostrophes etc.!) His style, in his vernacular, is "rapid"

We know he got into Southampton Uni to do Law so he's not dim - he's writing his blog for his fanbase not us but it's out there so open to criticism which is fair enough.
As to why he's doing the show when he's got a full time job (and the same with Chris) I think it's 'cos he did the Comic Relief thing, enjoyed it so much and wanted to learn how to dance plus the competitive element which he's acknowledged he loves.
Think I remember Chris doing a feature on Breakfast a few years ago with the blonde weatherwoman (back in the Mark/Matt days) when they did a Strictly dance together. Maybe he got the bug then & it's something he wanted to do.
Neither are doing it, it seems to me, to further their careers as such - they're both in work and, AFAIK, it's secure. They seem to be doing it because they love it and they'll put up with the hell of the exhaustion & unsociable hours because they're having a ball.