I think your friend is indeed right.
I am an 'out of the box' thinker myself and that is the way I have always looked at cases. It has served me very well over the years. I don't ever automatically assume that the murderer will be the one the majority normally suspects. I especially don't do that if I have seen no evidence supporting that theory.
Imo, the suspect in this case will be far from being the 'usual suspect' just like it wasn't in many other cases.
FoxFire, can painfully tell us all from their own experiences from searches they have been on in high profile cases where much valuable time and effort was wasted on what police perceived to be the 'typical' suspects.
In some of those tragic cases some of the victims may have been able to have been saved. LE too can get tunnel vision and sometimes it has even cost victims their lives.
The perfect example of that was when LE was convinced that the Lunsford family was involved and spent countless hours/days grilling them day after day trying to get them to confess to something they were never guilty of in the first place. Meantime for three long agonizing torturous days Jessica was right across the street right up under LEs nose being tortured, and raped repeatedly by Couey.

At that time the majority of the internet was also certain a family member was involved. And it has happened in countless other cases as well.
If this person is ever caught and brought to justice he will turnout to be anything other than typical or the usual suspect.
IMO