grammar - The use of "therefor" in my High School Diploma

I just received my High School Diploma and want to make sure the following sentence is grammatically correct.

The diploma contains the following line: "This certifies that [Name] has satisfactorily completed the requirements prescribed for graduation and is therefor awarded this High School Diploma"

I've read that "therefor" means "in return for" and "therefore" means "consequently." From those basic definitions, it seems like either word is correct here.

But I figure that just can't be right. At first I thought that it must be "therefore," but now I'm thinking that "therefor" (like they used) is probably more appropriate. Which is it?