A small or mid sized SUV usually has cargo space comparable to a hatchback, definitely less than a station wagon.
That guy correctly pointed out your logic is flawed, if you’ve been convinced by a salesman that the cargo space is something other than what it is, reflecting on that could make you a more informed consumer in the future. Getting annoyed at people commenting because you perceived them to have a ‘holier than thou’ attitude on it won’t benefit anyone.