I agree, I would feel it was inappropriate to help a student make friends or help with social communication.
I think that's different from facilitating academic networking - but I wonder if that's what the OP actually means? To my mind, finding a network of people with whom to discuss the course, isn't just 'socialising'. I've run workshops for students that cover this (amongst other issues).
But I also think asking other students about the course - if it genuinely is 'about the course' and not 'about the subject' - is probably a poor second to asking the lecturers/supervisors. Some students are much more able than others to email (or to email in an appropriate way), and they do tend to do better. It's a skill that's really worth learning: how to write something polite and well-timed that'll clear up confusion.
What exactly is it that you want the lecturers/supervisors to do? If he can identify some specific requests and email to ask for them, that might help. Eg., I had a student who emailed to explain that she found it really helpful if each quotation on a handout was numbered and each line of text was numbered - really easy for me to do, and seemed to help her - and I also had one who found it really useful to have a very quick break in the middle of the hour's lecture. So, I made space for informal questions at the halfway point, so she and others who needed to stop and take a moment.
What I'm getting at is that there are lots of things that can be done quite easily, so long as the student can ask for them (ideally, in advance). What's harder to deal with is 'Dear Dr X, I struggle with concentration, so could you remind me what happened in Week 1' or 'Hi Dr X, I struggle with concentration, so would you give me your lecture notes?'
That said, I do think it might be good for him to consider setting up a reading group himself? Would that not be a good alternative?