Likely true. As terrible as a selection as Kagan is, the good news is she is replacing a terrible Justice’s seat. The net loss is not great.
The net loss is time. An old leftist justice is replaced by a young leftist justice. Each time that happens the likelihood of a near term positive shift in balance become less. We don’t want to have all the old guys on the Court. Fortunately Roberts and Alito are quite young.