The only reason I can fathom someone would stage a crime scene in the shop is if they were trying to mislead the police into believing that MC was attacked by intruders. Not that intruders would be ruled out if the crime scene occurred in the house. However, if the scene was staged in the house, then the family would come under suspicion. Perhaps that was what the person or persons who staged the scene were trying to avoid. That is, if the scene was staged.
I'm not altogether convinced it was. The blood looked odd, but there could be a reason other than the scene being staged. What if someone rendered him unconscious with a blow to the head, and then he was lifted onto a tarp or stretcher. The head wound would begin bleeding immediately, even as he was being picked up off the floor, hence the drops straight down. Once he was on the tarp or stretcher, his blood would pool underneath him, rather than drop onto the floor. Not to say that I believe this is what happened. It could have happened that way. It could've happened another way as well. MC could have been rendered unconscious at another location, his blood drawn, and the crime scene staged in the shop so as to mislead LE into believing he had been killed there, rather than elsewhere. Or he could have had his wife draw his blood, they both staged the scene, and now he is in hiding while she attempts to "cash in" on his death. I don't believe that last scenario for a moment, but it's possible.
The other possibility, which seems the strangest of all, is that MC was attacked in the shop, and then the scene was staged to look staged, in an attempt to make it look as though MC had staged the scene, rather than someone else being behind his disappearance/murder. Just my humble opinion, but that would be an extreme example of overthinking it, if that was the case. If MC was not behind his own disappearance, I'm not convinced the perpetrators are criminal masterminds. If a family member is behind his disappearance, they have done everything possible to look guilty. Or at least they've done nothing to avoid looking guilty.