Hillary will now have to read the agreement, and find something in it that she claims to disapprove. To support this deal in opposition to Bernie’s withering condemnation of it could be suicidal for her in the Primary. Most Democratic groups are fervently opposed to this, and view Obama and Biden as selling them out.
But bear in mind that she was in charge when negotiations on this were initiated, which means that she approves of the way the deal was negotiated, and its basic outlines, if not each of its details.