The opening of your just-cited link reads:

>Democratic presidential nominee Joe Biden again ducked questions Thursday about whether he would seek to add seats to the Supreme Court, telling reporters he would not address the issue until after the November 3 election.

For me personally, when I combine that with his institutionalist remarks before he became the front-runner in the D primary, leads me to believe that he's not in favor of it, but tried to hedge once he won the nomination to avoid another irritation to progressives.

I do understand that your interpretation may be different.