Given the recent business transaction and the apparent rocky transition, it is perfectly natural that C & S would be considered persons of interest.
I don't think many people of sound mind actually thought C & S were directly involved with the disappearance.
Some people probably suspect that the business deal was not what D'Arcy thought it was and perhaps may have contributed to him being in a vulnerable state.
Since the robbery gone bad theory is not correct, and this was alleged to have been a gunpoint abduction, his state of mind would not have changed this event.
I think the flash point that ignited much of the animosity is the issue of whether or not the police were denied access to D'Arcy's room.
When one side says it is white and the other says it is black, the discrepancy of claims could hardly be more different.
Obviously this would create great suspicions on both sides.
Even if they were denied or discouraged, it probably had nothing to do with the disappearance and was merely a side issue, but looks highly suspicious none the less, especially for people who are already POI.
I think the thing that is so confusing in all of this is what is the motive?
What possible gain would C & S have with D'Arcy disappearing?
I can't think of any.
All criminals must weight the risk/reward and consider whether or not the potential gains of a criminal act justify the risk of getting caught.
It doesn't make sense to risk an extremely serious offence of kidnapping for no potential reward.
I think it would cost a hell of a lot of money to pay someone to do such a job and again, to what end/gain?
What possible motive would D'Arcy have to disappear?
I'd like to know if he intends to honour his contract with C & S as this could dispel any motive that I can imagine, which I would rather not get into here.