That's "right" in the sense that there's a 100% chance you'll upgrade to a bigger camper and never trade trucks until you die. People generally have a tough time thinking that far ahead.
If it's a matter of getting someone on the road safe and happy vs. scaring them off, I say get the 2500 and go for the DRW truck later if you decide you need that mammoth camper in a few years. TCs have a nasty way of being gateway drugs that lead to travel trailer and 5th wheel addiction too, and a 2500 will tow a lot more than it can haul.