I'm not seeing the term "allowed" on the page. Maybe it was edited since you posted. I'm thinking that if it was used, it was probably a result of English being a second-language or something similar.

I don't understand how the GNU GPL license would impact your usage of git. Do you intend to include git with your application?

I think the intent of this article is to show you the different ways you can implement git to solve a variety of problems. The GNU GPL license is largely irrelevant to end-users of software.