Well, we can't know for sure, but I don't think they got Derek with the long plan of waiting for Jordan. They asked Jordan, he said no, they moved on, then eventually they made LTE and found out he was willing to join, 5 years later. I don't think the plan was "Let's go with Derek until Jordan changes his mind".
It's like with the DT audition to replace Portnoy - Minneman auditioned, he didn't get the gig, Jordan liked him and made a collaboration with him. Should Mangini leave the band of his own accord and Minneman be willing to join, I guess we could hardly said that Mangini was a stand-in for Minneman (different situations, I know, it was just to make an example).