The first sentence of your post is correct, except that the word "can" needs to be changed to "definitely will at some point".
We (and probably every other dealer who sells repair supplies) have had dozens of orders over the years for glue from marine boat owners who either have the transom mount coming unglued, or the rigid floor. Zodiac does a pretty good job with what they do glue, and in the case of the wide transom mounts and your floor attachment, those parts cannot be welded. They have to be joined with adhesive.
If the failure occurred within the first five years, that's a warranty issue with Zodiac. Zodiac glue failures anytime in the first ten to twelve years are rare from what we have been able to glean, though we are not a marine inflatable seller. Usually the failures happen in the 13 to 15 year range, but keeping a boat in the sun will accelerate that a bit. The outgassing of the phthalates simply happens at a higher rate under constant heat.
We do have some more info under PVC vs. Rubber/The Great Debate on our website menu, but I doubt it will be helpful in getting the insurance company to cover it. If the boat is at all salvageable, it may be possible to strip the entire floor off, clean up the old glue, and re-adhere it. That's going to be an expensive fix I bet.