"The BASIC they did which we got ahold of the BASIC source code and enhanced t quite a bit was great."
Thanks! I think this is still talking about his high school volunteer hacking rather than the MS Basic era. (i.e. doesn't obviously support your "ported it".)
They got the source code of DEC Basic, studied it, "enhanced quite a bit" then wrote their own Basic which is similar to DEC Basic, and you don't think it is a derivative? Ok. It is a derivative in my book.