Seeing as the Cloud had departed from the Ohel Mo'ed (See Pasuk 10), why did the people not travel?
Seforno: Because they realized that the Cloud only departed in order to distance Miriam. 1
Da'as Zekenim: They did not travel because in honor of Moshe, the Cloud did not leave. 2
Hadar Zekenim: They did not travel, because the Cloud did not go to honor Moshe (avenge what Miriam said about him), since the Cloud was in her honor. 3
Pasuk 10 is discussing the Cloud above Machaneh Yisrael, and not the Cloud that showed them where to travel. Alternatively, it departed and returned, or went only up, and did not lead them in any direction. (PF)
Refer to 12:15:1:2*. This is not like Ta'anis 9a, where the Gemara says that the Cloud was in Aharon's merit. (PF)
Why could Yisrael not travel and Miriam walk behind - as diid other Metzora'im?
Oznayim la'Torah: Because Miriam required seven days Hesger (quarantine) outside the camp, which, would not have been possible as long as they were traveling. 1
In honor of the Tzadekes Miri?am. 2
On what merit did the entire camp of Yisrael wait seven days for Miriam to be cured before moving?
Rashi and Targum Yonasan: On the merit of the short time (seven days) that she waited 1 to see what would happen to Moshe, 2 when he was cast into the river (Sh'mos 2:4). 3
See Sifsei Chachamm and Ba'al ha'Turim.
Targum Yonasan (in Pasuk 16): From the fact that the whole of Yisrael -numbering six hundred thousand - the Clouds of Glory, the Mishkan and the well, all waited for Miriam for seven days due to the short time time that she waited to see what would happen to her brother Moshe, we can learn the great reward that is due in Olam ha'Ba for Tzadikim and for those who keep the Torah.
Because Hashem deals with a person measure for measure - although His measure of good exceeds the good that the person did. Hence the whole of Yisrael waited seven days for Miriam, even though she only waited a short period of time for Moshe.
