Maybe after a few beers, if I squint hard enough...
So here's a link with images of exactly what the vandals did. Now I don't think this sculpture looks anything like a vagina, but if you do then this link isn't work safe either...
http://www.bbc.com/news/world-europe-33189194
...because it looks like, er, um, you know, that thing that happens when, uh...
Regardless, it strikes me as less a case of raw vandalism and more a case of genuine (if vulgar) artistic expression.