The person you're responding to isn't asking for a material proof. They're pointing out that ontological arguments are typically seen as an "argument of last r

The person you're responding to isn't asking for a material proof. They're pointing out that ontological arguments are typically seen as an "argument of last resort" in a philosophical setting, and are making an (abductive) argument that the use of an ontological argument indicates a weaker position than the importance of the proof (the existence of a god) would otherwise suggest.