We have a 2012 Grey Wolf that we bought used a few years ago. Ive noticed the rubber roof has what I'd call "spider cracks" all over it. Some places are worse than others. I suspect someone might have...
I think you are correct in thinking that the wrong product was used on the roof. You should inspect where the roof is hidden, like under the AC shroud. It is only a guess if the Dicor coating will give good results long term. Maybe you could contact Dicor and get their opinion. Failing that, I would make a decision based on the prices of coating vs. a new roof.