Well, I'm thinking of the silicone as more of a safety precaution to keep your monitor from wedging the partition loose & potentially getting stuck/injured/what-have-you, but that may be me just being a particularly paranoid mom when it comes to the little legged ones.

You could always try it with your dirt substrate & see how well the partition holds...if you feel like it will wiggle too much, just silicone it into place. It's neither expensive nor time-consuming...just put the divider in prior to adding substrate & run a "bead" of silicone (i.e. a line of the silicone goo from top to bottom of the divider where it meets up with the cage wall) down the seams on each side. Immediately afterwards, dip your finger into a cup of water (have it on hand) and run it down each silicone bead to smooth it, and wipe off any excess with a paper towel. Let dry for 24 hrs, add substrate & you're good to go!

K~