It seems as if rawQuery() is unable to process data modification statements such as UPDATE or DELETE.
I don't know if this is by design of SQLite, or by design of the Android API into SQLite, or an accident of one or the other, but it would be nice if this were documented somewhere. It's possible that some part of some manual somewhere has a note on it, but when I brought myself up to speed on the tools I saw it nowhere; and over the course of two days worth of debugging to figure out why my code wasn't working, my searches didn't turn up any mention of it.
It appears that the only way to modify rows is to use the update() method. There's nothing wrong with that.
What is wrong is the fact that when given an UPDATE query, the rawQuery() method simply does nothing, without throwing an exception, logging anything, or in any way indicating that something has gone wrong.
This is the second piece of developer-hostile behavior I've come across since I started doing Android programming earlier this year. Here's hoping that Google will fix it, and anywhere else in the system where errors mysteriously disappear. If a method is passed illegal instructions, it should throw an exception. I can think of no justification for silently swallowing an invalid instruction.