>only the company that contributed the files originally can replace the license headers of the files granted
That is a policy statement, not a legal statement.
This is an important distinction. For example, an Apache project can not release software containing GPL code. That is a policy requirement. But legally, anyone else, outside of Apache, is free to mix ALv2 and GPL code together, if that suits their needs. The licenses are compatible in that way.
You should not confuse the stricter policy requirements incumbent on an Apache project versus what the license permits any random person to do.