It’s really not an equality thing. A religious woman traveling alone would do the exact same thing. This is the case even if both people are religious. It’s not sitting next to each other that’s the problem. It’s that a man and woman who aren’t married to each other can’t touch which is all but impossible when on a plane seated in adjacent seats. On the El Al flights I’ve been on, the flight attendants are well aware of this issue and already have scoped out potential seats they can move a man OR a woman to should there be a need.