On Discovery: Ethical Euthanasia?

[scarythedave]

You stumble upon a crypt lined with some form of stasis chamber. Assuming you understand how to do both, how do you choose between reviving the chambered and disabling their life support? Our instinctive choice is to revive them, or at least to allow their continued stasis, but if they have been there for hundreds or thousands of years, the difference in immunology may make them immediately susceptible to terrible diseases that would've been super-bugs in their day. Alternatively, they may carry some relatively common disease considered destroyed for aeons: their release could wreak havoc.

Not the cheeriest of morning thoughts; what are your thoughts on the scenario?