I'm pretty sure the only real issue with the license is that the license is not clear about what the limits of "this software" are.
My understanding is that the following are your main concerns:
1. Content, including blog posts, talks, and images. You don't really want those reposted, especially if misattributed or altered.
2. I know you really don't want people to come to rely on the software have put out there on the net, especially in any way where you would feel obligated to provide support, notifications about vulnerabilities, etc.
For #1, clarifying that the contents of the `blog`, `gallery`, `talks` and `static` folders (and perhaps `template` too) are not part are not covered by the license, would effectively take care of this. (I also agree that it probably won't stop people from hosting such modified copies, especially if they are using scraping techniques, as opposed to running the code, but at least then it is completely unambiguous that they are violating the license.)
For #2 the existing nonstandard license, and warnings in the readme are probably mostly sufficient to make this clear. Plus honestly overall the code is pretty tailored to you. If I were to try to create a blog based on your code, I'd want to rip out the galley and talk sections, would need to redesign or remove the webmention support (or run a stripped version of the `mi` api), remove the patreon support, remove or modify xe-conv, change the cloud flare ping code, remove signalboost (I'd be too small to meaningfully boost anybody) etc. And all of that on top of creating the content, creating a stylesheet I like, creating new templates, etc.
"All rights reserved" is obsolete language (there's a long boring story behind that) without legal effect. The way copyright has worked internationally since the late 70s, you don't even need a copyright notice but not having one will limit your remedies (and make proving your case very difficult -- always use a copyright notice). Your work is copyrighted automatically when created. If no additional license is provided any copying not under Fair Use is illegal. Licenses like the many variations on Creative Commons allow for copying under the explicit terms of the license (minimally requiring attribution). Apache, MIT and the 3 generations of the GPL do the same for software. Enforceability, especially by authors not themselves wealthy or backed by a wealthy patron, is another matter. It's a rich man's game, and become even more so over time. If someone steals your car, you might get the authorities to step in. But if they steal your written creation, even though violation of copyright is a crime in many jurisdictions, you're on your own.
