The spines shouldn't be much of a problem puncturing the bag since the bags seem pliable enough to keep from being punctured, but be careful not to net him.
I've heard that this often hopelessly snags the catfish. At this point, the only thing that can be done is to cut the net, leaving your new friend swimming around in a bad mood with a chunck of green netting attached to his back! Not the best of circumstances for a good first impression.
I have two Raphaels, and if they are any indication, you'll need to worry about this. The barbs are VERY prominent on these fish!
Also, if you have a waterfall type filter return, net it off. I found that my Raphael, being the good nocturnal creature that he is, decided that the water return on my Eclipse 12 looked like the best cave in the tank. He was no where to be found on day 2-that is, until I lifted the filter on the top of the tank! He was swimming away up there trying to get into the impeller housing (not a possible task, but he was just swimming against the current).
He had apparently gone up the water return (this is nearly level with the water surface when filled as per Eclipse's directions), had SOMEHOW gotten around the rotating BioWheel (they're strong enough, so he probably just forced his way through against the wheel's turning in the water flow), swam up over the lip holding the filter, and found a gap that he was able to exploit to get under the filter into the water flow.
Fortunately he was able to stay in the water flow, and didn't suffer any ill effects when I was forced to overflow the water return and float him back into the tank around a removed BioWheel. Eclipse commented that this was "such a strange little fish", but I doubt that it's the first time that it has ever happened.