This article at DNAinfo (linked from a linky page in the NYT) highlights the opinion of a transit authority board member, David Jones, whose objections are 5-fold:
1. Triviality. It's a mere "quality of life problem" that shouldn't preoccupy the police.
2. Poverty. It's a crime people commit because they're insufficiently rich. So it's "like Victor Hugo, 'Les Miserables,' persecuting people for stealing bread." And then the punishment is to collect a fine, but these are "people who have already indicated they don’t have money."
3. Race. Jones either knows or imagines that there is a disparate racial impact: "I’m also worried that if you start to look at the demographics, who’s interfacing with the criminal justice system on this, it’s generally young people, blacks and Latinos."
4. Illegal immigration. It will lead to deportations. "Even before the Trump victory, I would’ve been concerned because I don’t want young people having an interaction with the criminal justice system that doesn’t involve some very serious activity.... Now it’s heightened — we just don’t want to give more ammunition and more reason to deport people who have engaged with us because of poverty."
5. Sneakiness. The NYPD uses plainclothes officers to catch people in the act. Why don't they just have "a big sign there and a policeman under the sign"? Then that turnstile wouldn't be luring impulsive youngsters to leap.