David Levy said on https://en.wikipedia.org/wiki/Wikipedia:Village_pump_(proposals)/Archive_AD#Salted_pages:
I'm surprised to learn that cascading semi-protection is possible, as this enables anyone with a non-new account to semi-protect pages. That's a far worse problem than the display of that message (which would require developer intervention to change) and I don't believe that cascading semi-protection should ever be applied for any reason. In my opinion, it should be formally prohibited via the protection policy. —David Levy 18:34, 27 January 2007 (UTC)
In fact, the situation is far worse, since when semi-protection cascades it becomes full (per T10658). Thus, users can full-protect arbitrary pages by editing a semi-protected page with cascade enabled.
The only reasonable solution I see is to disable cascade completely for semi-protected pages.