Howdy Doc, I've heard that about the lard too but I've always wondered, why is that "going rancid" comment only associated with lard? I've had crisco go bad after sitting in the cupboard for a long time and it's just as rancid as lard gets. Also gotta wonder, who makes the Camp Chef stuff? Maybe the Crisco company???? :D
Honestly, I don't think that it makes much difference what you season it with but personally, I always use lard or bacon fat which is well.... uh... lard.
If you use the item regularly, I don't think it'll go bad no matter what. I suspect that the cases of so called "rancid" taste are from people who only occasionally use an item. They clean it and then wipe on a too heavy coating of lard before putting it away, expecting it to be fine the next time they use it in several months or even years. Well, it won't be whether you use lard or shortening.
I do my cast iron about like I do a gun cleaning. Get it clean by the method of your choice, wipe it with oil, then wipe nearly all the oil back off and put it away. Basically, just leave a very thin coat. On a pan that is well seasoned, you don't hardly even have to put anything on it for storage.