StartSSL charge you for revoking that exposed certificate, so your choices are you pay for the revocation, or wait until the certificate expires.

Now if there had been a problem with their signing certificates then I would have expected them to revoke anything affected for free and offer replacements similarly at no cost.

OK, they could have done that anyway (or perhaps offered a discount on the revoke charge) as an good will gesture, but they didn't, so what.

All they claim is to provide free certificates for non-commercial use, and that they do provide. If people read something else into that it isn't because they were deliberately led to.

Though many people picking up a cert without really knowing the infrastructure won't know about revocation infrastructure and such so might have mislead themselves by having not read the Ts&Csm.