I interpreted the "deposit but can't withdraw" policy more as an attempt to avoid an immediate bank run. It could be a good business decision whether they're solvent or not.

The purpose is not to prevent bank run. People had plenty of time to run if they wanted. The purpose of stopping withdrawals is to make sure people don't take advantage of any bugs that are still present. Like the poster here who reports having $7M in his account, rather than the expected few hundred.