It's one thing to assess the foundation - it's another to make assertions regarding the details that counter the main argument one is trying to support.
In this case, the main argument for Bruce is that Rudy entered via the window/that this was a burglary. He then presents the argument that Filomena was messy, and this is why there were clothes on the floor and thus why glass from the window was found on the clothes. However, this leaves a bit of a problem for the main argument - i.e. where is the evidence that Rudy went through Filomena's room looking for valuables?
Yes, if you're discussing only the actual entering of the window, it would be possible to do so without disturbing the glass on the sill. However, we must also take into account that Rudy necessarily grabbed onto the windowsill to pull himself up on the downstairs shutter. We also must realize that the glass shards would not have only been in front of the hole in the glass, instead they would have, to some extent, dispersed along the windowsill. Then we look at how Raffaele would have had to maneuver his arm, while holding himself against the wall using the windowsill to steady himself, so that he could reach the latch - or he would certainly have cut himself on the glass (or at least heavily risked it...much more likely that he was bracing himself, no?).
Then we have to account for the lack of glass in the garden from the window breaking - so something was in place to block the glass from dispersing to the garden at the time the rock broke the glass. Unlike so many would, apparently, like to believe...glass shards don't fly only forward or fall directly down when a glass pane is shattered. The lack of glass in the garden is telling.
Now, we have to account for the lack of marks on the wall from Rudy bracing himself on it. Nor are there marks from when he pulled himself up/over the windowsill. Again, this is all done without so much as disturbing the glass shards on the windowsill.
Add the lack of shoeprints in the garden, lack of garden dirt in Filomena's room, apparent lack of searching through Filomena's room, etc and the Rudy as a burglar scenario just doesn't match what evidence we have.