That article is not at all well-reasoned. There's a core of truth, which is that even with 100% vaccination a population may not always have effective herd immunity from measles, because the vaccine is not 100% effective over all timespans, and the threshold of immunity required for effective herd immunity against something as insanely infectious as measles is quite high.

But the author goes far beyond that conclusion and rails against the very idea of herd immunity, and claims that since herd immunity may not be possible in practice when dealing with measles, there should be no stigma against opting out of vaccination. These conclusions are very weakly argued, and the obvious counter-arguments are not addressed.