It's MIT licensed, so anyone can incorporate based on the original author's work and turn a profit. He is not owed anything. This is an eventuality you are implicitly accepting when choosing MIT over GPL.
Of course they're legally allowed to do so, it's just a question of does it make sense vis-a-vis their stated values about community and rewarding the people who has worked on the project.
GPL or MIT doesn't really matter all that much here; the only difference is that with the GPL I'd have release all the source. There is nothing in the GPL stopping me from starting a Compiler Inc.™ SaaS based on gcc that "compiles code as a service".