If you already use an add-on that manipulates routes, you will experience issues.
Therefore, the advice would be instead to keep that option as your desired route and install the Route Changer add-on. Or, if you already have that add-on installed then just use that to change the old route 'xenmediagallery' to whatever new route you like.
I imagine this will all be much less painful in XF 1.2 when the aforementioned bug is resolved and the core has the Route Filters option.