I was looking at this question, and the answers don't really cover any viewpoints aside from that of the Roman Catholic Church. The second answer quotes Grudem, but the answerer's claim that he speaks for all Protestants isn't exactly accurate. So, according to Luther and Lutherans, do angels in heaven pray for humans on earth?
Most assuredly they do.
The traditional doctrinal standard for the Lutheran Churches is the Book of Concord. One of documents in the BoC is the Apology of the Augsburg Confession, also called the Defense of the Augsburg Confession. It is an explanation of one of the other documents in the BoC, the Augsburg Confession. The Apology was written by Luther's chief collaborator Philip Melanchthon rather than Luther himself.
From the 9th Article of the Apology defending the 21st Article of the Augsburg Confession:
Besides, we also grant that the angels pray for us. For there is a testimony in Zech. 1:12, where an angel prays:
O Lord of hosts, how long wilt Thou not have mercy on Jerusalem?
Although concerning the saints we concede that, just as, when alive, they pray for the Church universal in general, so in heaven they pray for the Church in general
In addition to believing that the angels intercede for the Church, Lutherans also believe that the saints at rest do the same. The answer you mentioned does not represent the Lutheran position. I doubt it represents the current Anglican position. Asserting that it represents Protestants in general is overreaching.