Taking it at face value, seems quite plausible that's being thrown off by there being a disproportionate/larger number of poorer people voting left wing, and poorer people tend to be less educated. It doesn't in itself mean anything as far as the rightness or wrongness of the political alignment. Just that, if so, poor people on the whole, are more likely to vote left than right.
Lies damn lies and statistics.
What's definitely bullshit though is saying that someone who can answer more science questions with better use of English is "smarter". It means, again, that they're probably better educated. Which isn't the same as intelligence.
And finally, it's just a bad point to make. Because it says absolutely nothing about any actual position or opinion. It's just pathetic "people who disagree with me are dumb" bullshit.
And yes it's just as bullshit when people come up with ways to show the reverse conclusion of conservatives being less intelligent, which people also do all the time.