To be precise—I have to correct myself—, I don't disagree with it. I just can't agree with it without some kind of proof. I've also stated that in a few posts. There's not reason to assume that metol negates glycin's activity.
You will likely agree, that the difference between developers using only HQ and only Ascorbic Acid will be not comparable to the difference between MQ and PQ type developers. The Metol will change the developer entirely, and only little of PC versus PQ can be explained by comparing the Q and the C alone. This is all the proof I need to assert, that whatever properties a Glycin only developer brings to the table will play a minor role in Ansco 130. Please also note, that an MQ developer like D-76 is much closer to a Metol only dev (like Haist's variant) than anything made from HQ alone.
Metol forms a superadditive pair with hydroquinone, why would it kill the effect of glycin? Who knows, may even be the other way around, i.e., that the presence of metol increases the action of glycin.
The more active Metol will be somewhat dominant over the by itself much weaker Glycin. Apart from that I would follow Lachlan, who has decades more experience and light years more depth of insight into photographic industry that I'll ever have. His argument "photographic industry could have easily upscaled Glycin production if it had any benefit" holds a lot of water.