Dumb Question, we store all the bitcoins sent to cold storage in a vault that is a faraday cage shielded to protect against something like this.
Well, it might not be that big of a deal, but if it's what you're doing, I wouldn't think it would *hurt* to advertise that fact. There would definitely be people who choose your service over others just for that.
On a single piece of media that could spontaneously fail for any reason?
I would be more comfortable hearing that the private keys were kept in two places and were maintained in such a way that, for example, an unexpected death of the custodian of those coins wouldn't result in their loss, while meanwhile ensuring that they're adequately protected from theft.
I don't know that they don't have multiple copies, or what the data is stored on.
I'm just pointing out that there are people who will hear about the solar flares due this year, think, "Holy crap! My computers might not be safe!", and then sometime down the road see the "Solar-Flare Safe!" line on their webpage and jump right on it.
I have no comment as to the usefulness of it. Just that it shouldn't *hurt* sales to put it up on their website, and might actually gain a few.