1. How do you know you have a tear?
2. Glute activation also depends on the depth of your squat:
The effect of back squat depth on the EM... [J Strength Cond Res. 2002] - PubMed - NCBI
3. How do you know they did not activate? You had EMG analysis while squatting? Unless your ass has fallen off, it is impossible to squat without using your gluteus maximus. The GM functions to straighten the hip by retracting the thigh and extending your torso. Unless no movement occurred at your hip joint, which is impossible, your gluteus maximus activation. Glute med and min will activate to stabilize your thigh during the squat, and some assistance during hip flexion.
4. Glute maximus activation is greater with a wider stance, but only under high load:
http://www.castonline.ilstu.edu/mccaw/hpr482/EMGREAD_files/4540 McCaw and Melrose squat EMG.pdf
Unless there is significant weight being used, which increases the need for the GM to activate secondary to an increase in forward lean/hip flexion-extension, stance width does not significantly affect the activation of the glute max. Med and mid may get activation more, but their contributions to power in the squat is minimal.