N_locktime! Of course, rather than having the datetime in the script;
use the transaction n_locktime flag to prevent the TX spend before the certificate validity is there.

So you have 2 TX's, one the 'loads' the key with some value pre-signing (so it can be included in the cert), and another generated post-signing that allows these funds to be bounced somewhere after the cert is invalidated by time.

This is seems to be equivalent to the revocation certificate; as long as it is signed by the UTXOC key at key generation time, it can be submitted by any anonymous party any time after n_locktime. This is advantageous over the PGP revocation model in that anyone can submit this on your behalf, and has a good reason to do so.
My suggestion would be you provide an incentive that someone other than the key owner could be bothered including the TX -- I'm thinking fees.

If you can construct the "revoke funds" TX with sufficient fee, miners have an incentive to seek out these previously signed TX, published publicly, and include them in the next mined block past the n_locktime unix time. It seems this requires some public place to store these transactions; maybe this is a service that could be offered by exchanges or even CAs?

I like that this doesn't actually prevent the key holder from revoking the certificate at any other time before the validTo date, as the owner is free to construct a TX that invalidates the 'sign time' revocation TX as a double spend.

Also, grau, this is also a good idea. I had not considered tracing the source of the UTXOC as a a way of bootstrapping the trust.
There is a potential here to do away with long-term trusted root distribution.
As long as the CA could prove solvency with an unbroken chain of value transfers, one could use a known trust anchor by inspection of the sources to generate the next valid root.

I guess my next step is write the validation routines; I wanted to publish the paper and code last night, so i didn't get to finish the whole lot before public release.

Thank you DeathAndTaxes, grau and Peter R for your very valuable suggestions