All over the article you posted:

and since Floorp currently has no advertising, my own salary is, of course, zero. It’s just not going to last.

I have made many plans, including earning development money on this projects, but all have been derailed by open source projects.

There is some code in the closed source code to prepare for this. If these are forked, my hundreds of hours will have been wasted.

The purpose is to learn how to publish code that cannot be used for forking as open source.

I have to obligate the folks to choose whether they want to pay me or help me code.

So hes forked the open source Firefox, added some polish, and is now miffed that others have taken his forked project and forked it themselves, because it cuts off a possible income stream he had planned. That code, the things he intended to profit from, is whats hidden in the “closed source” part of the repo. He says he will open source it eventually, likely after he figures out a way to profit from all of the code Mozilla kindly let him fork for free.

He doesnt want anyone else to profit from the hundreds of hours of code hes added to the millions of hours of free code hes currently trying to profit from. This is of course a very reasonable and consistent moral stance in line with common open source principles.