HVAC people just really hate heat pumps. I ran into the same problem for my rental which is basically the poster case for it (small size, well insulated, Midwestern area)

They never have specific answers to anything. "It just can't do it."

They don't have any response when I say that these are used all over Scandinavia without problem.

Unless the person spoke with has installed one and had specific problems that they can articulate, you can ignore them.