Question:

Yes, according to a recent letter from Director Mayorkas to Senator Leahy, a Regional Center can utilize indirect job creation outside its area of geographic scope to satisfy investor's job creation requirements.

The question as asked implies that you already started a business and are looking to "join a Regional Center" just to take advantage of indirect jobs. It ultimately depends on the particulars of the situation, BUT, from the little information in the question posed, it is probably not a viable option.