Any source is "biased." It's whether they're up front about it that counts. Which is why just about anything from the "objective" media is BS.
Should I just give up on him?
No, just be sure he understands that he'll be responsible for his own choices. That is, should he decide to major in Great Inuit Literature of the 17th Century, you're not going to be there to pay his bills when he - unexpectedly - can't find a job. Financial independence is a big motivator in determining one's politics; liberalism tends to fade when you don't have other people's money to engage in it.
Financial independence is a big motivator in determining one’s politics
A very good point. You could also add personal responsibility for oneself to that.