I see a simple size problem with the device.
You can not have it wide enough to accept any cock size, if you do, you can not insert it easily anymore.
Even if some women wanted to go there and try, I guess it would not be comfortable at all.
In that case, size matters...

Now even if we had a practical, easy to use device of the sort:
What about women using it not as a protection, but weapon... The device can't discriminate between a rape and a consented intercourse...
Also, should you have a guy with the device attach to his cock, how can you prove he's a rapist and not victim?

But since this is all bullshit, it doesn't matter.