He’s obviously completely ignorant on the issue and doesn’t even realize machine guns have been heavily regulated since the early 20th century.
That’s not the argument you hear from most leftists, most leftists use the appeal to emotion or misleading vividness. They don’t care how common a shooting with actual automatic weapons is, which I am willing to bet I could count all the shooters in the U.S. who actually used fully automatic weapons with my fingers post 1930s. That’s not the point of the leftist though, it’s all about the “what ifs” (appeal to emotion) or the well event x actually happened (misleading vividness, because it ignores the reality that such occasions are EXTREMELY UNCOMMON).