This was going to happen sooner or later.
In all seriousness, this appears to be at least as much of a police issue as anything else. The NYPD has been less than renowned by New York residents the past couple of years. It's entirely possible the officers wanted to arrest these two for unrelated reasons and simply used "manspreading" as an excuse to do so. Especially since subways aren't usually very crowded that time of night.
So I'm not going to blame feminism for this case in particular.
And for those with little experience with New York's subways: the seats aren't small, but are quite hard and have a weird curve in them. Every seat is indented downwards, meaning it is virtually impossible not to take up, say 20% of another seat. You either take 1 or 2. And if you are going to be sitting for a long time in a quiet time of the day, taking two seats may seem reasonable. I personally prefer standing, but it's very much a matter of personal comfort.
Love and tolerate.