Do you have any evidence for this? I've not heard anyone make this claim before, and I'm curious how much validity it may have.

That's a circular argument. Why are education systems liberal?

And where's your evidence that earlier "most institutions had a conservative slant"?

I understand how a circular system can sustain itself, but then how did it turn from conservative to liberal?

A public, tax-funded university exists by coercion. This is going to attract the people who are results-driven and be repulsive to an ideology-driven person. Therefore, it can reasonably be expected to suggest coercion as an allowable tool for solving any problem.

Under socialist ideology all universities are public and tax-funded.