Does this mean they will not look at it at all?
I am pretty sure this is correct. Maybe others can comment. When are you retaking?
If so, what would happen if I decide to retake it and NOT indicate on AMCAS I did?
Your application should be reviewed with respect to your previous MCAT.
But, with that said, this is per the AMCAS 2015 Instruction Manuel
"It is important to include your scheduled MCAT test dates on your AMCAS application,
and keep this information up to date. Medical schools have no other way of knowing that
they should expect additional MCAT scores from you."
This makes me think if you don't update planned tests on AMCAS, schools may look negatively upon finding out later you scheduled a test but did not inform them, just so that you could get your application reviewed earlier. But I could be wrong.
If you submit now without planning to retake, you may benefit since many schools are rolling admissions, so if your stats are not the highest, applying earlier puts you up against fewer applicants per total interview slot available than say in September/October.
I think if you are pretty confident you can improve score and you are taking the exam within the next few weeks, indicate on your AMCAS. If you are not taking the MCAT until September, you may reconsider how necessary it is to your application, since you will not be reviewed until October (which many schools have assigned significant number of interviews already).