Avi K: The strongest argument that the Rambam did not hold that way is his own actions, i.e. the proof he did believe there is a contemporary mitavah to war against the Muslims is that he willingly took a job helping the Muslims. Could you imagine a Gadol ha-Dor who took a parnassah working for the Third Reich. Remember he worked for Salahdin. Personally. Up close. Saw him regularly (he was the family doctor).
Remember, your position is to to enforcce your view, which is basically a 20th century hiddush (okay, Shabatei Zvi held the same way, but no one else), you are willing to sacrifise the community of Bnei Torah that now lives in Eretz Yisrael, since if the zionists declare open season on the hareidim then the Bnei Torah will be forced to bring medinah in order to survive. Fortunately, most of the leaders of the zionist parties (except perhaps for Yair Lapid) are so fanatic.