Except that doesn't translate to reality. The problem with it is that there is an option that doesn't have them voting red either... simply not voting. "Vote Blue No Matter Who" is idiotic to raise as a reason why he can do it, because of a variety of reasons, so let's cover a couple.
1: The student vote is already incredibly fickle, it's hard enough to get out as is. As in, despite the idiotic saying, they historically -already do not vote-. Despite this fickle voting pattern, they are a reliable blue vote hence why they are so important. If there are 1,000,000 students in X region and only 10% vote, that still 100, 000 votes. Now, repress that vote. Stab them in the back, and have them be surrounded by the normal apathy. Well congrats, you just dropped that 10% to 1%.
2: "Vote Blue No Matter Who" historically is farcical and actually entirely untrue by how it's used. Now, what do I mean by this? Simple, it's actually false by all metrics outside of major cities, and -even then- only really holds inside the absolute democrat strongholds like San Francisco, New York, etc. Lets look at Detroit, a Dem stronghold outside the major coastal bubble. Solidly Blue right, no way that there could be any republican gains, right? Actually, since 2008 Republicans have steadily gained there. Slowly, but an increase of ~6% that's steadily increased cycle over cycle can't be ignored. Also, Dem Support has steadily decreased... except the last election where it saw a completely normal, not at all fake vote impacted bump of 2% with absolutely no correlated decrease in Republican votes.
In short, anyone who spouts "Vote Blue No Matter Who" as some sort of gotcha or counterpoint actually knows nothing about voting trends.