They've now posted this on their FB site:
Thanks for your comments on this, we've been reading all of them.
We have decided to remove the phone sock from our online accessories range
The fact the response has been so passionate shows there is a real issue here, one that I believe the product is trying to address – but clearly not effectively.
This is tricky. There are two sides to consider. One, as you've presented here, sees this as a literal message to girls and women, especially blonde ones, that maths (and by extension, science, engineering, technology: STEM) isn't for them. At worst, this perpetuates the negative stereotype. This was absolutely not our intention, nor, I think, the intention of the product.
The other side is that this is a message taking aim at these exact stereotypes, and trying to challenge that thinking, which is how I feel it’s intended. It is how many of our customers interpret it.
There is a place for using parody to make a positive point. I was encouraged to read the response of one lady on Mumsnet talking about the phone sock, who said that she would've loved to walk into a boardroom with her phone in this and challenge stuffy thinking.
But we’ve listened to our customers who are offended by the product; many have not interpreted it in a positive way. And that is why we are removing it.
We will, however, look to continue our work to encourage women into STEM roles, and I look forward to doing what we can to continue to address this issue.