It's not sexist because it's one person with power over another regardless of gender. Gender is irrelevant here. That's the whole point. You can change the genders, the races, the sexuality, it makes no difference.
The stronger person is going to be the one doing the choking in this picture. If the female had been the stronger one the same would apply. It's a sexist stereotype to assume all men are stronger but no such assumption is evidenced by the picture. To assume it is would be similar to assuming any violence depicted from a racial majority to a racial minority is racist. When of course it isn't. Either it's acceptable for all or acceptable for none. Affirmative action for both gender and racial minorities is ironically sexist and racist respectively, despite good intentions.
Egalitarianism is the only way to go.
The stronger person is going to be the one doing the choking in this picture. If the female had been the stronger one the same would apply. It's a sexist stereotype to assume all men are stronger but no such assumption is evidenced by the picture. To assume it is would be similar to assuming any violence depicted from a racial majority to a racial minority is racist. When of course it isn't. Either it's acceptable for all or acceptable for none. Affirmative action for both gender and racial minorities is ironically sexist and racist respectively, despite good intentions.
Egalitarianism is the only way to go.