I was momentarily jacked up, I could hardly type or think due to the profuse amount of f-bombs fomenting in my little pea-brain.
However, I've developed a little wisdom over the years so I went back an re-read your post once more. What is the "microwave/hood?" If this is a combination unit, that sits right above the range he might be right.
I've seen a few combination units in our neighborhood almost burned up from the homeowner upgrading the cooktop/range sitting underneath the unit. We removed our combination unit & replaced w/ a venthood. We bought a mw & put it into a shelf built into our island. We couldn't have kept the combi-unit w/ the cooktop we replaced our builder-grade unit with. We didn't see a ready replacement & just assumed we had to do it the way we did. Didn't think there might be another brand of combination mw/venthood that might work.