That would also seriously shock the biological filter, which I think is what he's trying to avoid.
First off, what size tank is it, and what is the stocking, with sizes?
If it's lightly stocked, doing the above will be fine, as long as feedings are reduced for a few weeks.
if it's more heavily stocked, you may have to hang a bag of your old gravel in the tank, just clean it in unchlorinated water first, it will help neutralize the shock to the system some. Still reduce feedings.
The thing here is, that the tank has been fed a certain amount of food reguraly. The beneficial bacteria colonies only grow to that level. When you remove a large portion of that colony, the remaining ones may not be able to process all the waste. It will cycle faster than a freshly set up tank, but it is still going to go through a mini cycle.
So in a nutshell, remove fish, water, gravel, replace gravel, add water, then fish. Be prepared to do water changes more frequently, and test for ammonia and nitrites every day. If you see either of these getting high, do a water change. Note it is better to do more frequent, smaller water changes than a few large ones.
Good luck, and tell us how it goes.