This post is only an update to the previous post. Recently I found an even more elegant solution in order to disable seam.deployer. Instead of removing the package from JBoss AS deployers folder we can provide a jboss-scanning.xml file which as documented on JBoss Wiki is able to remove certain files from scanning process.
So, a better (and also less instrusive) workaround is to provide under war/WEB-INF/classes a jboss-scanning.xml file with the following contents:

<scanning xmlns="urn:jboss:scanning:1.0">
  <path name="servlet-1.0.war/WEB-INF/classes">
    <exclude name="seam.properties"/>
  </path>
</scanning>