Who's throwing the shower, your Mom or the MOH? If your Mom is helping out then maybe you could compromise and just have him show up for part of it. My FI has absolutely no interest in being around a bunch of blathering ladies, but my best friend's FI showed up for part of hers, mostly because some of the gifts (especially honeymoon related) were for both of them. We took the sparkly pink tiara off her and made him wear it as he helped open gifts, and everyone had a blast (although I think by the time it was over he was in desperate need of man-time).
I see nothing wrong with your FI being there if he wants. The wedding is his as well right? My FI is coming to my shower and nobody thought it was odd.