I suspect many graduate entry careers require at least a 2:2,and more likely a 2:1. So I guess your lad would fall outside this. I don't know anything about IT specifically, but it sounds as if he's not interested in this career anyway!
I guess the overall question is: if he resits the 3rd year, whether by attendance at uni, or distance learning, is it likely that his grade would IMPROVE enough to gain a reasonable classification?
I suspect he needs to find the answer to these questions, in detail.
It would depend on a variety of things;
Was he awarded a pass degree, as he would have failed an honours degree? Normally a university would award a classification if at all possible (this may have changed in the last 15 years tho?!)
Essentially is it a question of motivation or ability?
If he did repeat - how would the 3rd year university treat his previous credits? Essentially, what average would he need to achieve during the third year to get the classification he needs? Some universities have 30:70, 50:50 between yr 2 and 3, and some don't count year 2 at all. Depending on his motivation /ability he would need to aim at an institution which gives him the best chance of passing well.
I remember a flatmate who was deperate to do a Msc which required a 2:1... Her year 2 marks were pretty low... (I think low 40s) ....she calculated it... The way our uni counted the modules, a 30:70 split, she would have to scored in the high 60s wirh some 70+ modules just to get a 2:1...she decided on this basis to change her goals, as there was no way she felt she could improve this much on the harder 3rd year modules. In the end she achieved a low 2:2.
I think given the cost implications of repeating,( could he get a fee waiver - were there any issues which prevented him from doing well?? ).... He needs to be very clear what he's aiming for and the likelihood of achieving this.
If the answer that his likely outcomes would be a 3rd class degree, he would need to discover how this would be viewed in his potential career path(s) . In my subject, anything lower than a 2:2 (and often a 2:1) would likely preclude from further study, and would not be acceptable for graduate schemes requiring a good academic degree. Sadly, there is just too much competition.
I think it is very easy to get into the mindset of a 'degree or nothing', he needs to be very clear, and honest with himself over the likely outcomes!
Are there other routes to what he wants to do?