I think there's still a potential difference between who is presiding, and where the presiding leader sits. The current Handbook does speak specifically about the "presiding" aspect, but from what I can tell, is silent regarding where anyone needs to sit during sacrament meeting. Including the Bishop. I'm not saying the Bishop should be sitting with his family in the congregation

, but I do find it interesting that there's no instructions requiring the presiding leader sitting up front (many units throughout the world meet in various locations which do not have a stand or maybe even pulpit). So my takeaway is that the local leaders (Bishops/Stake Presidents) have discretion to determine what they feel is best for situations where the Bishop would be "alone" on the stand... or what to do when a Stake Counselor attends but could possibly wish to sit with his family and still be the presiding officer.
I know there's a lot I don't know, so if anyone knows where additional guidance is provided, please share!