I don't think kidneys work for free. I would accept its negligible but, the effort of managing the osmotic processes which take water out of the GI tract and putting them into the kidney to become urine implies energy is spent.
Quantifing that cost, and the exhaled CO2 which might indicate energy stores in the body are being consumed interests me. I say this because during the period I stopped eating like a complete chungus I also started drinking a lot more water and I am sure the eating change (no nice lunches and much less nice dinners and much much less nice wine and strictly rationed amounts of chocolate because without red wine and chocolate my life is over) did cause most of the weightloss I still wonder how much came from the water.
Fine article says "none" well, absent better evidence I better take that onboard.
Kidney stones said drink.
( Point 4 about the weight loss has a really "duh" proposition in it at the end. Sure, water helps lose weight, when you replace drinking sugar with it. Who would have thought ingesting zero calories instead of hundreds would do that !? /s )
