No, she doesn’t believe him at all. The points she brings up in the article make it clear she thinks Trump and Vance are full of shot on the matter and just desperately back pedaling right now:

American women are not stupid, and we are not going to trust the futures of our daughters and granddaughters to two men who have openly bragged about blocking access to abortion for women all across this country."

After Welker pointed out that it seemed Warren wasn’t buying Trump and Vance’s spin on this, she stomped down even harder, saying, “Don’t buy it? Just read it. JD Vance actually sent a letter last year to the Department of Justice to enforce the Comstock Act. And remember he did that, and then Donald Trump picked him to be his vice president. The only way that we’re going to protect access to abortion is to have a Democratic Congress send a bill to Kamala Harris. She will sign it into law, and then we will restore a right to half the population in this country, and no longer will a woman have to go into an emergency room and be told she’s not near enough death to get the medical treatment that she needs."