I think that about 2 percent of Muslims support radical Islam. And about 2 percent of those act out. Or said another way are the actors.
I believe that this guy's father is a good example of the 2 percent who support radical Islam. And of course the shooter/killer is an example of the 2 percent of the 2 percent who are the actors.
Some may think that these percentages are too low. But I don't think so. Because the fact of the matter is that most followers of all faiths, really don't take their faith that seriously.
(Please remember 'most' is simply 51% or more.)