Although I can't speak for Hugh, I believe he was just talking from the perspective of nage. I had the same initial reaction until I thought about it, then I realised he is probably right.
Isn't uke also studying aikido?
IMO, uke and nage should be trying to do more or less the same things via their connection to the other person. And while yes, it is absolutely true that one should not be pushing or pulling, there are many many situations in which wrapping one's fingers around the contact point (wrist, shoulder, neck, forearm, whatever) can facilitate aikido-compatible movement.
In my experience, people who have been told that one should never, ever, grab in aikido tend to respond by making their hands overly stiff so that they won't let their fingers curl by mistake. That's not it, either. Human hands are amazingly versatile instruments: surely we can think of some alternatives that might lie in between "rigid death grip" and "rigid hand blade."