"It must provide APIs" isn't an argument. It can't be taken literally because it's clearly false. And it can't be taken in any other form because the author doesn't tell us what those forms might be.
It continues, equally poorly stated: "Millions of users create the content expecting it will be widely available. Locking down an API breaks that social contract." Now that IS an argument, but it's not a good one for a surprisingly large number of reasons, the simplest of which is that websites like Reddit are widely available regardless of a free API.
Finally, we get to the only actual statement of merit: "The short sighted thing about these API fees is they will harm the company in the long term." Yes, that's quite likely true. Is that the whole argument? That this is a short sighted plan? Companies are free to make stupid plans. They do it all the time, and you are free to stop doing business with them. "Must" doesn't enter into it.