What has the student's union got to do with anything beyond the small number who have any involvement in the students union? Compulsory payments to the student's union have always been a scam pumping money to activists working against the interests of those making the payments. When I was at university the activists used to tour the refectories every lunchtime in the run up to students union elections, because the turnout was so small it made them look bad. Nothing happened in my time at university on which anything about my political views could be assessed, other than perhaps the rude way we told those trying to get us to vote to leave us alone to enjoy our lunch.
As usual, you're focusing on the supplementary illustration about the Student Union, that you hope is arguable, and ignoring the main point. My judgement of the political sympathies of the student body as a whole is based on direct personal experience of the hundreds of individuals I knew, at exactly the point in time you're trying to say that there were next to no people with soft left tendencies in the student body, not on the composition of the SU's elected officials. It might be a bit tricky for me to jump back in time and get an affidavit from each of them to provide material support for my case, but I think most people would agree that there's a tendency for the young voter to be left leaning (and I could quantify that if forced to), and that tendency is stronger in university students.
Just to drum the point home, voting intentions by age and by education for the last general election:


The broad left always gets more votes from the young and well educated and that's been true for as long as I've taken note of politics. The question here is would a political party be cynical enough to take note of that, and re-engineer higher education to include people who would not otherwise have gone into tertiary education by encouraging the creation of syllabi and courses that would accept people who hitherto where not thought of, or likely to think of themselves as 'university material' in a bid to create more 'natural' voters for themselves? Given the sort of unprincipled power hungry chancers that are naturally attracted to politics, I'd say yes.
Are you really telling us that you were so socially isolated at university that "
nothing happened in my time at university on which anything about my political views could be assessed". I find that unlikely given how quickly you'll offer an opinion nowadays. For that to be true you'd have to either have talked to no one, or talked about nothing interesting - half the fun of being at university is sitting up
way too late at night arguing about how to set the world to rights with friends and people who were strangers at the start of the evening.