I dont know any engine builder(and I know a couple) who would make such a sweeping statement. Any builder worth his salt would have to analyze the entire package before making that statement.
People have been using Nitrous and alky with awsome power for years. Jack Barfield, who you mentioned in your earlier post, did this 20 years ago.(actually, jack is a biofuel engineer by trade an has ran on dogshit and lemonade, smelled great) The only problem is delivery. Alcohol carbs cannot flow enough air, plus you loose vacuum signal when you spray. And nobody uses it with mechanical injection because most cant tune the car properly without nitrous, and the n20 just makes things messy. Plus the cold nitrous and latent heat evaporation of alky can make for some broken exhuast valves and fuel puddling in the runners.