By "moral baseline", I am simply referring to the minimal standard of behavior we should expect from other animal rights advocates. For example, the president of one AR organization was forced to resign when it was discovered that she was using the group's funds to pay off her morgage. So, in this case, they had a moral baseline which stated that, at the very least, you can't steal from the group's treasury for personal use, and then expect to remain a member of the group and be allowed to continue to be an activist.
Different people can disagreee on where the location of the moral baseline should be. Gary Francione proposes that the moral baseline should be veganism. We might reject this proposal, but we would still have a moral baseline which says that certain behaviours, such as the one described above, are unacceptable, regardless of what good this person might otherwise be doing.
(My animal rights FAQ)