Gravely sinful for the artist, yes.
However, that is just another example of how God uses his artists even though they don’t know it.
On the surface a piece like that would be all Satan’s doing, but it’s quite possible the project started out as God’s work (selecting Mary),
Satan, as usual, takes advantage of the opening to do his manipulating (the feces **and **finding someone to display the work as ‘art’)
and yet God still retains the upper hand because the display results in a rally by all Christians in defense of their Mother. Rosaries get prayed (just think about the number of rosaries we’re talking about here and the impact that must have on the souls in purgatory, on our nation!), Mary gets placed in the forefront of many peoples’ minds and hearts who otherwise were forgetting about her.