Interesting article, Max.  You asked:

"...It is in reaction to their immigration policies of the past?"

Only indirectly, IMO.  Denmark's new found "xenophobia" (as the global left would no doubt call it) is in reaction to the facts on the ground, as outlined in the article you referenced.  To wit:

"Muslim leaders openly declare their goal of introducing Islamic law once
Denmark 's Muslim population grows large enough - a not-that-remote prospect If
present trends persist.  One sociologist estimates, every third inhabitant of
Denmark in 40 years will be Muslim."

Currently the most popular baby boy's name in Denmark is (you guessed it) Mohammed.

Sadly, it may be to late for Denmark.

It may - or may not - be too late for much of the rest of Europe, which also seems to be awakening at this late date from its slumber.  (Some Europeans at least are awakening, while others slumber on, concerned with non-relevant issues such as global warming.)

MWL