The fun with silicone molds is we can put the mold split line wherever we want. We can encase the entire master, just so long as its easy to remove from the mold with the closest replication and least amount of sanding and least amount of detail affected. Silicone provides the flexibility to stretch the mold slightly for cast removal.
I try to avoid running a mold split down a 5mm peg. If at all possible, I prefer to encase it and run the mold split down an area that's easily sanded with the least amount of detail. Like a corner or edge.
Here's an example of both.
Here, the peg is fully encased currently in clay, which when removed will be replaced with silicone. Also the mold split line goes through the top of the head where there is no detail and down the middle of his face again where there is little to no detail and a natural ridge dividing the face in half and then along the neck edge to the back side where the mold split is moved to follow the natural edges between detail to avoid as little disruption to detail as possible when sanding.