I'm sorry are you saying that there are no student republicans? that's a very misinformed opinion if you believe that.
[1]http://www.pewresearch.org/fact-tank/2016/05/16/millennials-...
My point was moreso that in the US at least there is a pronounced difference in political affiliation based on age. Notably, that is an old quote, it just seems interesting it holds up.
It's saying that a 20-year old conservative is necessarily heartless, and a 50-year old liberal is necessarily stupid. I don't see how either of these follows; I know plenty of young conservatives who care deeply about other people, and old liberals who are very smart.
It's just a lazy meme.