I've not eaten one that big, but no, they're not disgusting at all, Bear Grylls is a farking actor, he's not the real deal. He has survivor knowledge, but he's being paid to put on a show, not show you practical shit for the outdoors. Ray Mears and the canadian fella are much better, of course you can filter everything they say through an RVAF point of view, ie no need to cook rabbit or anything else, except things which are toxic without cooking (though for me, that would only make it food in survival situations). Also it shouldn't be human vs. nature, it is human returning to its home in nature. We part of, not apart from nature, no matter how badly we try to delude ourselves.
It is far better to take advice from Jon Young, Tom Brown jr., Tamarack Song and others who've 'gone native' or more accurately reclaimed their native heritage.
As for the grubbies, they are squishy, but being averse to that is learned behaviour. They are quite delicious and will take on the flavor, like anything else, of whatever they've been eating. Palm grubs will taste like palm, wood grubs will taste like wood, earth grubs will taste like tubers or whatever they've been chawin' on.
That is for white/beige grubs and meal worms.
I've eaten green caterpillars that have been super bitter and made me a bit nauseous. Read up on entomophagy for more info. Also study native cultures, they've got tons of great knowledge on eating bugs, which are usually delicious and great sources of easily digestible fat and protein.
Note: Edited for lack of proper conveyance!
