Seems like typo in documentation, because:
1. "LAC" will be automatically enabled in case, if you will perform upgrade from 7.1 SP2.x version to 7.5.x version.
2. If I correctly remember, if "LAC" is disabled in 7.5.x version and you're going to perform upgrade to higher 7.5.x release version, then "LAC" will not be automatically enabled.
Thanks,
IP.