Page 32 of Just Ride, he says that clipless proponents say there are two advantages: more power to the pedal because it's not being absorbed by a soft, flexible shoe sole, and it's easier to apply power all around the pedaling stroke. He then goes on to claim neither of these is true, and presumably intends that race riding is included. He goes on again to say there should be a benefit while racing in terms of keeping a smooth shoe on a tiny pedal.

He does discuss why the soft shoe thing is not true. Not sure I get it and agree, as yet.

He addresses the 360 thing by saying that nearly nobody, and nobody tested in published physio lab tests of pedal forces over 360 degrees (I think he mentions muscle activity testing as well) pulls up on the upstroke, and reasons that if tested riders (usually trained racers) don't, then his customers don't pull up, so there is no occurrence of 360 degree propulsive pedal forces.

Can any of us do this and create a fallacy for Grant? Yes, I can with my loose toeclips. But I can't keep doing it long enough to make it a benefit over a decent-length ride. There may be some brief (a relative term, but for me it means much less than a mile) advantage, and if I was a racer I'd explore this to see if the trade-offs are worth it.

But yes, Grant did address the topic aand present an argument but did not present his sources, dot his i's and cross his t's. So yes, I'd grade his argument as at least a suggestion.

Your argument sounds like concern for your foot falling off the pedal or otherwise shifting position without a good retention system. I'm not sure Grant addressed this point, and I know I'd like that security feature if I needed it. Here I'd think a tightly strapped toe clip can help as well. I have tried a cleated shoe with tight straps and it does feel more secure, but there are other issues that I don't like.