Yes, it is. However, Mike dislodged the gun from behind the toilet with both hands. How could he avoid leaving prints onthe pistol's barrel and cylinder?
Probably would have been difficult. But every plan has snags.
Perhaps it's easier for the authorities to raise prints from the grip and not the barrel?
In any event the important thing is that he's not caught with the gun. Everything else the Family could fix if need be.
Also critical is that he's never arrested for that or any other crime. So his prints would never have been in the system to be compared against.