You do not get to comment on another country's internal policies, have your PM and his ministers call their country out on twitter, while comparing them to Nazis, then start a big fuss about expelling their ambassador (which is a very hostile move in diplomacy), and then get overrun by extremists and become forced again to try and placate them with even more broadsides about that country...
without that country eventually taking action against you. Everyone has their limits, why should France or the EU meekly stay quiet while our show never ends?
European over-sensitivity to the holocaust ought to be challenged, but not in the way we have done it: as a reactionary aside to conflating two loosely related matters, while posturing and interfering with their internal politics.
Also, if you expel the French ambassador, not only France, but many EU countries will begin with sanctions and withdrawing their ambassadors. The lines of credit we get from them, the aid, the debt relief, the trade and exports, their input on the FATF etc... are all very real. Your protests have no effect on the French, but they will have an effect on your own pocket.
And all this happened because we chose to stick up for some kid who came to another country, with different laws, customs, and beliefs, who take no view on blasphemy (legally) and he decided to murder his teacher because he caused blasphemous offence.