Technically the French were acting as the benefactors of Muhammad Ali and Egypt until the Second Egyptian Ottoman War sending French officers to train his soldiers and sending French made arms and munitions to his army and Navy so their involvement is more understandable to an extent. The Military Mission had also been in Egypt since the early 1820's and many former Napoleonic French soldiers and officers joined on the side of the Egyptians..
......which didn't prevent the French setting foot in Mount Lebanon, or more explicitly the British occupation of Egypt....
Edit: You were referring to the 1860 intervention by France. That was a direct result of the 1860 massacre of the Maronite Christians and the incompetence or unwillingness of the Ottoman Empire to stop the violence in Lebanon. That action by the French had the approval of the British, Austrians, Prussians, and Russians, and then later the Ottomans so there really wasn't anything wrong with what they did in terms of Status Quo/balance of power dynamic. After all France was fulfilling its role as the Protector of the Ottoman Empire's Christians.
The British policy is more nuanced than I originally stated. While they preached the preservation of the status quo ad nauseam, they weren't completely against disrupting it if it was to their benefit; liberating Greece, occupying Egypt, etc. More often than not though, they were in favor of the status quo, especially when it came to Russia.