Because he could be easily manipulated is my guess.
DBs reckoned they (murder squad) hated getting Patel for a case.
Another more recent comment from Streathamite suggested it wouldn't have been the police who picked Patel, it would be the Coroner.
All in all, I don't buy the Patel-in-conspiracy idea.
One thing that *has* come out is the failure to pass on the information reported by a PC who saw the assault. The Met say they told CoL*. CoL say they weren't told. It would have pertinent to post mortem (rubbish pathologist aside).
* Fairly sure it was CoL, but might have been IPCC. On phone, can't quickly check.