OK, you piqued my curiosity, so I looked it up. Omni is a economy PPG product. It can be either A/E or A/U. It can also be a low VOC paint. On the PPG website, it says the A/E can be "upgraded" to a two component technology if desired. That means you can use it without the hardener, but if you want it to be really good, then use the hardener. It is kind of like the ads for one of the "quicky" paint chains that advertised that you could upgrade the paint with an urethane additive.
Paint is like fiberglass resin. It will dry without the catalyst, but it won't have full strength or durability. Once the catalyst is added, it causes a chemical reaction that causes the resin to be very hard, strong and durable.
Randy