You made an absolute statement . . . "business leaders can never lead an engineering firm." All that is needed to disprove that statement is one counterexample, because then it has to morph into "some business leaders can lead an engineering firm and some can't."

Ironically given the subject matter, this is similar to how math proofs work . . .

It's the nature of the word "can't" which allows a single counterexample to debunk an argument.

If the grandparent poster really meant "It is quite difficult", then it seems that we have arrived at a more accurate representation of the original argument, and thus 0xbadcafebee has been contributing greatly to the discussion.