This is a completely hypocritical and dishonest position. Rabbis of the Conservative movement are not halachic authorities. No woman goes to them seeking permission to get an abortion.
The Conservative rabbis are asking that the government not hinder them in exerting a religious authority that they do not in fact have.
It's not a religious thing, they're entering the political sphere. Even the Reform movement acknowles Halacha in their opinions on issues like abortion or homosexuality, then floats off into it's a modern world, and we know things the sages didn't, and who are we to judge.
They are correct that it's a legislative issue. I doubt they intended that condemnation of Rowe v Wade.
And while they may not grant "permission", women do consult Rabbis on personal issues such as abortion. IMO a Rabbi, irrespective of his political views, who doesn't explain the Halachic position on abortion in the context of that consultation isn't doing his job.