These people are fools.
Maror isn’t horseradish. Lettuce is maror. The Bavli and the Shulhan Arukh are clear that you use hazeret- romaine lettuce- for maror.
Horseradish seems to have been used because they didn’t have green vegetables in Europe and its use is foolishness and lacks halakhic valence.
We use romaine lettuce washed and prepared ahead of time for the sedarim, and eat horseradish during the seuda when we have fish.