The Michigan Supreme Court reversed, holding that Mr. Stross missed his opportunity to raise a challenge to the ordinance.
The Court of Appeals erroneously reached this conclusion, in our judgment. At the time defendant’s variance was granted, then-current MCL 125.585(11) required a party to challenge the constitutionality of the variance within 21 days. Defendant’s painting the word “LOVE” on the sign clearly violated the “lettering” condition of the variance. Because this statute prescribed the relevant procedure for challenging the constitutionality of the conditions, defendant was obligated to challenge these conditions in accordance with this procedure. His failure to do so precludes him from raising his constitutional challenge eight years later. (source)
It seems awfully strange that the Michigan Supreme Court would brush off a Court of Appeals case like this. However, this illustrates the danger of accepting a variance to an unconstitutional ordinance.