Alvar should've kept quiet until it was needed. Alvar may gain more with earning berengars trust but the church has a deeper reach in their territory. At least he should've made the decree as private as possible so the church wouldn't know of it
And once more your ignorance shows. Schleswig-Holstein had the same amount of people as the rest of Denmark. Combine that with the fact that the danish King was German and it only was on the say so of Bismarck that the request for entry by the Danish king into the German Confederation was denied.