I can’t speak for Matt Slick, but let me suggest a different alternative that I think occurs to many fundamentalist Protestants. It goes like this:
(1) Protestant alleges that Catholics worship Mary,
(2) Catholic says “no” and proceeds to explain the difference between latria, hyperdulia and dulia,
(3) Protestant understands Catholic’s explanation but finds it unconvincing. To Protestant, the Catholic distinctions between the concepts are distinctions with no difference, distinctions in name only,
(4) Protestant tells Catholic what he thinks,
(5) Catholic says “no” and reemphasizes difference in concepts,
(6) Protestant cannot understand how Catholic believes such stuff and concludes that Catholics actually do worship Mary and are engaged in either self-deception or duplicity when they insist otherwise.
Please note that in both instances the hypothetical Protestant and Catholic referenced above are acting in good faith and generally understand each other’s position. They just don’t buy each other’s position.
Please note further that I am NOT the hypothetical Protestant here.

I simply offer this as another (I believe) likely explanation for some of the differences between our faiths on this matter.