As I mentioned in my other comment, I give a thumbs up to Movable Type, particularly in regards to security. The only database access is done on the admin side. When you publish anything, it generates pure html pages. So only you access the database. Users only access html. There are no complexities between these two arrangements.
Movable Type takes just a little longer to set up than WordPress, but hey, many of us here are hackers right? Plus you can tweak the code to your heart's content.
Static HTML is also a lot less resource intensive.
I think the main thing in the way of people using MT is that lots of people get their first introduction to blogging on some free WP hosting first and consider the switch to commercial shared hosting to be an upgrade.
People like this wouldn't see switching blog platform as an upgrade so much as an inconvenience.
Weigh PHP, categories, comments, human-readable URLs, and convenience against retaining control of your content or (potentially) the server it lives on.
The people running Sendmail in the '90s went through all these arguments too.
It's hard to understand how a blog package could have created a worse track record than Sendmail (though I can tell you how). But it did.
I rejected your premise. I didn't try to solve your problem. Your need for PHP, categories, and whatever else doesn't make any difference. Wordpress will be as, insecure as it will be independent of your need for it not to be.
Again: avoid Wordpress. If you can't, you have my sympathy.