(And BTW I like OSI’s definition!)
Instead of claiming the words “open source” always mean OSI’s definition, it’d be better to clarify up front that you’re talking about OSI’s “Open Source Definition”, which is (effectively) a trademark or term of art and does not preempt all possible definitions of the phrase. (Special note that the words “open source” do not always refer to code.)
The turf battle over the words free and open seems silly to me, with both sides arguing that the other side’s word literally means something other than they intend. Stallman has argued that open means source available, and OSI has argued that free means price. Both sides are right, and both sides are stubborn too.