By your logic the people laid off from other companies would also be the kind that weren't worth keeping. If everyone is firing bad developers and looking for good developers, where do all these good developers magically come from?
I would not take it as a given that the individuals laid off were the worst performers at the company. It could be that they were highly compensated and deemed too expensive, or happened to work in the wrong department/business unit.
easy: you add "We only hire rock stars" to your job postings.