I don't have a Nurture mold, but they look like they are no different than any of my other wooden and silicone molds I use in my oven for CPOP, so I'd go ahead and put it in the oven without worries.
If it will fit in your oven, all I would suggest is that you place it on a tray of some sort inside the oven and make sure the wood does not touch the metal sides of the oven. Make sure to pre-heat your oven BEFORE you put the soap inside, as ovens tend to heat much higher than the number you set it at while it is pre-heating.
If you are willing to moisten the surfaces with a little water, that will help, but if you don't want to take it all apart again, AND the soap is fairly new (not old & dry), I'd go ahead and bake it at 170° F for at least an hour, but depending on how big your mold is (a huge slab?), then I'd probably bake for 2 or 3 hours, checking surface temps of the soap with my IFR thermometer. Then I'd leave it inside the warm oven (turned off) for several hours.
If it were me, I would take the soap apart, moisten, then wrap in plastic wrap (kitchen plastic used for wrapping food), then put it back in the mold prior to the bake. The plastic wrap survives just fine, so no worries about it starting on fire or melting; it doesn't.
But if that seems like too much work, try it without.