Using maven profiles to control build execution

You’re thinking about it a bit backwards: have the profile enable the behaviour, not disable it. This is just what profiles are best at, and is exactly your case: you only want the steps to be run in certain circumstances. So you might have something like:

<profile>
  <id>source-jars</id>
  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-source-plugin</artifactId>
        ...

And in fact there’s an example just like this on the maven-source-plugin usage page. When you need to generates your artifact, use mvn -P source-jars (or whatever). That’s it! If you only need to do this at release time, the release plugin even offers a way to define the profiles to use right in the release plugin configuration.