if your gonna use silicone go to church.....bunnings.....and buy a required size tube of automotive silicone (last i looked it comes in black and clear) should work a treat and stay flexible plus water won't bother it....guess bathroom silicone could be the same but automotive is designed to withstand uv also so good choice i would think, this is considering the wood is sitting ON the glass meaning no load bearing to factor in, i got no idea how much weight it could hold if it was holding wood onto the side of a glass panel
wanna know the trick to making it look neat and professional? mask the area 5mm or so out from the area with masking tape, use a wet rag to smooth the area making it look all neat and tidy then remove the tape, hey presto looks the goods.