Armor All used to use dimethyl silicone which causes dry rot over time. Now they've switched to water based emulsions but that old formula still haunts their perception in enthusiasts minds.
Truth is armor all won't hurt anything really. Its essentially the same as any other protectant. Thing is 303 Aerospace Protectant has more UV inhibitors than Armor All so it protects better. This is also why 303 is more expensive, but oh so worth it.
Hope this helps.