From the article I linked to
But an argument from silence is recognized by all to be quite weak. It implies that one must have almost total evidence before demonstration is possible. If this is the case, one could argue cogently that there may have been airplanes in the time of Christ." Dewey M. Beegle, Scripture, Tradition, and Infallibility (Grand Rapids: Wm. B. Eerdmans Publishing Co., 1973), p. 178.
If we followed this method of argument, we could prove Luther believed in Santa or Bigfoot, simply because no evidence exists to prove he did not I think it's important to keep in mind, it seems Catholic apologists do not have any positive evidence to offer that Luther actually believed in the Bodily Assumption of Mary. The closest they get is the 1522 quote, and this quote never affirms Mary's Bodily Assumption.
We can at least give this apologist credit for noting Luther's later disdain for the Feast of the Assumption. Catholic historian Thomas OMeara points out:
In 1544 the Assumption is abandoned as a feast; the Ascension of Christ alone is recognized: 'The feast of the Assumption is totally papist, full of idolatry and without foundation in the Scriptures. But we, even though Mary has gone to heaven, should not bother about how she went there. We will not invoke her as our special advocate as the Pope teaches. (The Pope takes away veneration due to the Ascension of our Lord, Christ, with the result that he has made the mother like in all things to the Son.)' "
I gave the link with my original post.