analogizing the "colorability" test in a hybrid-rights context to the "likelihood of success on the merits" standard for preliminary injunctions and to the pre-AEDPA test of a "colorable showing of factual innocence" required for an evidentiary hearing discussed in Kuhlmann v. Wilson, 477 U.S. 436, 454, 106 S.Ct. 2616, 91 L.Ed.2d 364

applying compelling interest test where plaintiffs demonstrated hybrid-rights claims