It is either an innovation or something that has been abrogated, and its very best—though in truth there is no merit in it—is no better than a Muslim’s praying toward Jerusalem after that orientation had been superseded.
That judgment applies when the deed itself is taken as an act of devotion. As for the accompanying indulgence in ordinary customs—food, clothing, play, or relaxation—these, too, are annexed to that religious festival, just as the festival is annexed to its own faith rather than to the religion of Allah, Islam. It is as though a group of Muslims were to invent a new feast, go out to the open plain, and perform on that day acts of worship and social practices akin to those legislated for the two legitimate festivals, Eid al-Fiṭr and Eid al-Aḍḥā; or as though they set up a shrine to be circumambulated and visited in pilgrimage, laying on food and the like for those who take part.
Now, if a Muslim detested that practice yet still altered his routine on that day—just as the innovators alter theirs in some or all everyday matters by preparing special food, decorations, clothing, increased expenditure, and the like—without intending it as an act of worship, would that not be among the most heinous of wrongs? The same, and indeed worse, is the case of conforming to those who have incurred wrath and those who are astray.