Ask HN: Creating a Hosted Version of an MIT Licensed, Open Source App?

I've found an open source app on Github that solves a specific development problem that I had really, really well. It's MIT licensed.

The author has been working on it for over a year and a half.

I would like to start a business with it, creating a hosted version of it.

I did reach out to the author and told him my plans. He told me that he would be bummed if I beat him to the punch and creating the service. But I haven't seen him do anything with it that would show progress on a commercial version. I don't know him at all and would not want to partner with him.

Should I feel bad about taking an MIT licensed app that I didn't develop and creating a commercial service from the work of someone else?