Well, obviously if they (Richard and Susan Sibella) did not have a son named Richard, they would be out of the running. But even if they did, you would still have the same problem of determining whether that was the same Richard who attended Cambridge and was ordained at Peterborough.
Viewing it another way, what evidence do we have that sets the parameters for identifying the proper Richard who did attend Cambridge and who was ordained at Peterborough?
(1) We know that Reverend Richard was ordained a deacon in 1622 or 1623. Different years are given by the Church of England records and by Venn's Alumni Cantabrigienses. Given the ambiguity in years at that time, I would allow for either being possible.
(2) We know that Canonical law required that Reverend Denton be at least 23 at the time of ordination. Therefore, he must have been born no later than either 1599 or 1600.
(3) We know that when compiling their histories of thousands of Cambridge alumni, Venn and his staff reviewed church records and observed that "almost invariably" the Cambridge graduates who were ordained into the church were "within a year or two of being 23." Therefore, if Reverend Denton must have been born no later than 1599 or 1600, he is very likely to have been born no earlier than 1597 or 1598, unless he were the exception to the rule. Being the exception is possible, but unlikely according to Venn's observations. That would mean he was most likely born between 1597 and 1600.
(4) The only two Richard Dentons I found who were born between 1597 and 1600 were (a) the one born in Fishlake, Yorkshire in 1599 and (b) the one born in Tonbridge, Kent (southeast of London) in 1600.
(5) The DNB, The History of Long Island ... by Thompson (1843), and Walter Krum's articles from the 1980's to 2004 all say he was born in Yorkshire. (I am unaware of any other authority that says anything different about his birth place.) The only Richard Denton born in Yorkshire between 1597 and 1600 was the one baptised in Fishlake in 1599 and whose father was Edward Denton baptised in Fishlake on 26 September 1568.
The above simply applies logic to the evidence we have in order to find a solution. Obviously, new evidence might suggest a different outcome, but the odds point very strongly in this direction.
I suppose another alternative would be to find all Richard Dentons who might have become the Reverend and then search for written histories that reveal each Richard's life and hope that one of those histories says that Richard went to Cambridge and was ordained at Peterborough. Ultimately, doing it this way, the problem still comes down to finding evidence with respect to each Richard that would identify him as the one who graduated from Cambridge in 1623-4 and who was ordained at Peterborough in 1622 and 1623 (plus or minus a year).