The claim here is that vegans are hypocritical in both claiming to be against the taking of life (animals) and being for the taking of life (abortion).
This is in line with the plants feel pain, i.e. that vegans are for blanket "preservation of life". Whether that's a bacterium or a human, it's all the same. The actual point that vegans make is about reducing animal and human suffering and increasing human and animal well-being. It's just about not "taking a life". Taking a life is only meaningful in a state wherein killing you diminishes your well-being and hurts you.
Most abortions are within 7 weeks of pregnancy, which is within a month of implantation. It's not even clear that the cortices that might be regarded as consciousness develop until quite a few months later into the pregnancy.
Political issues are hard. Religious zealots press hard to make abortion illegal even in medical emergencies, and therefore the shove comes back in the other direction to fight tooth and claw for every week of pregnancy, because liberals see even a slight decrease in the window is a gateway to total illegality. Moderation or intelligent discourse in this context is a stupid idea because you just get run over.
So regardless of the ethical calculus, people are willing to make moral concessions that lack the clear thinking that they otherwise might not make if not poisoned by this kind of discourse. I'm not defending it, just simply saying it's a layer of complications on the first two premises of "vegans tend to be [political category]; [political category] people support X; X is not compatible with veganism; therefore vegans are hypocrites."
Animal agriculture still hurts people, the environment, animals, and the people consuming animal products themselves. If you think that vegans should also ditch being pro-choice, then that's a great perspective and deserves an argument! But that doesn't invalidate the original argument. Carnism still hurts people, the environment, animals, and yourself, the only thing is you've stated some fact that isn't related to countering any of those arguments, just related to the people making them. But those conclusions still stand on their own merit.