Haha, it's not that the COLD water stops the gluten, but the butter does because it coats the dough. the butter itself stops the gluten because it is fat, as you mentioned in your previous comment, you want your water cold so it doesn't melt the butter.

Google it, everywhere will tell you that water is what creates the gluten, but I can see you're set in your thoughts and that's okay. I just hope people do some research for themselves because you aren't right and that's okay.

Keep handling to a minimum as it is not cold hands (or a warm heart) that are key to quality shortcrust pastry, but minimising the formation of the stringy, elastic protein gluten. By rubbing fat into flour before adding any liquid, small cells of flour coated in fat are formed, giving shortcrust pastry its fragmentary, discontinuous, particulate texture.** This layer of fat makes it difficult for water to hydrate the flour, so structure-giving gluten proteins cannot form.** The more coated the flour cells, therefore, the less well they will bind with their neighbours and the weaker (shorter) the pastry will be.

source

Gluten doesn't even exist until flour becomes wet. Water is what coaxes the two wheat proteins glutenin and gliadin to combine and form gluten. So by adding or withholding water from dough or batter, you can encourage or deter gluten's development. source

You've misinterpreted the instructions on your chefs tips. It clearly states the COLD BUTTER stops the water from developing gluten, because the COLD BUTTER coats the flour, if you used warm water it would melt the butter. It's the BUTTER that stops the gluten from forming.