Thank you, that is a valid objection; small contributions are likely to be inhibited by the use of an unfamilar language. But not all of them; trivial typo fixes, translations, ports, build and configuration changes etc do not require much understanding of the language. Nor do testing and reporting bugs, perhaps the most important class of small contributions.
But what I really wanted to challenge is the sad prevailing idea that some languages are "common" and the rest "strange". The statement in the article could be interpreted that way, although I am confident that Ms Henson does not suffer from that delusion herself. It is not helpful in making "uncommon" languages less so, even when this has great merit.
(Also, some "helpful" contributions that you receive as a maintainer of a free software package makes you wonder if the language-as-barrier is such a bad idea...)