I have a very strong feeling that Markel (along with other officials) has been paid off (by the Saudis and others) to let in all the unemployable young men of the Muslim world, in order to prolong some degree of social stability in Muslim countries. As such, orders are likely sent down that doing anything to make Muslims feel “unwelcome” will be bad for the careers of the police officials.
We’ll see how long Merkel lasts.
Long term, I don’t see a solution to what to do with violent men who have no skills, nor interest in working, other than killing them all.
Do you?
Forcible repatriation.
Jesus is the only solution. Other than that, there really isn't another satisfactory solution short of what you suggest.