Yup. The purpose of a bona fide slide is to arrive at the base safely. If the base in question is second base, that means you need to be able to get to the base AND STAY THERE. If you can't, it's not a bona fide slide. I for one am glad that the studs-up sliding tackle, which gets you a red card in soccer, is no longer part of baseball.
But that was not what Werth did--his studs were down. As far as the sliding tackle, he took Walker out AFTER he threw the ball. This is the equivalent of calling back a touchdown for a chop block or targeting, and if that is the case, if the rule is intended to protect the defensive player, then OK.