Certainly open to being corrected if that's wrong. But as far as I know it's a bit premature to talk about this being a "tax on depositors at other banks". It seems like these actions ensuring stability in the banking system may be beneficial to everyone.
If it turned out that all SVB assets were worthless and a HUGE special assessment would need to be levied to cover deposits, I would agree that this could be a moral hazard. But right now I think it just looks like prudent management.