Quite interesting. I personally think the "more decorated" side would still have been mounted facing out while worn, in this case. From a functional point of view, I also cannot see a good reason to suggest otherwise, especially if the prongs serve as catchers. It does vary, but a general rule of thumb is that the Tsuba sits approximately one fist from the body when sheathed. Taking sword angle into account, the prongs shouldn't interfere with the body. From a drawing sword point of view, there may be some hindering for the hand reaching the koiguchi. Less so though, than compared to having the prongs as hand guards