Forget defending, what about tolerating? Cryonics is something you criticize as a hobby. For me, cryonics is a matter of survival. It's my body those things will be done to, any my belief (correct or not) that how things are done matters to my survival. You've said that you don't believe anybody's survival actually depends on cryonics because it won't work.
And this can't just be because current organizations are not competent. If she were committed to being signed up for a hypothetical future ultra-competent organization the moment someone puts one together, it would do wonders for her credibility as far as I a concerned. At present she gives me the impression of a nosy outsider who feels the need to offer condescending advice and harsh socially stigmatizing criticisms to a marginalized group she neither likes nor identifies with.
Before you extrapolate from yourself - are you sure that you're even a sufficiently typical cryonics advocate, let alone a typical enough example of a disinterested third party?
I recently found something that may be of concern to some of the readers here.
On her blog, Melody Maxim, former employee of Suspended Animation, provider of "standby services" for Cryonics Institute customers, describes several examples of gross incompetence in providing those services. Specifically, spending large amounts of money on designing and manufacturing novel perfusion equipment when cheaper, more effective devices that could be adapted to serve their purposes already existed, hiring laymen to perform difficult medical procedures who then botched them, and even finding themselves unable to get their equipment loaded onto a plane because it exceeded the weight limit.
An excerpt from one of her posts, "Why I Believe Cryonics Should Be Regulated":