A stack trace shows that Maxima got stuck trying to compare the left-hand side to items in the assume database. (It reaches that step after trying some other things.) Some of the assume db things are floating point values of constants such as 1.161..., 2.718..., and 3.141... -- that's how floating point arithmetic comes into play.

I think the only way around the problem is to strengthen the floating point comparison -- catch the error and retry it with bigfloat arithmetic, maybe. I don't think it's reasonable to try to avoid the floating point arithmetic in comparisons, since that would mean avoiding the assume database -- I wouldn't want to try to reimplement the comparison functions.