While I likewise have no desire to get into a "tussle" over this topic, let me just add a few thoughts:
1. meditation is not exercise, and is a completely different endeavor for the body (actually, it's more of an endeavor for the mind and spirit, but the body is inseparable from the two); we're coming very close to conflating the two here (meditation and exercise), and that's inaccurate. And, therefore, unrelated to what's good for a particular blood type.
2. The object of meditation is not stress relief. It's often a beneficial side effect, but it's not the end goal.
3. If you "don't get" the value of meditation, then yes, I DO think you're doing it wrong. True spiritual meditation is a real challenge, and frankly, not everyone is up to the challenge.
4. I also value the benefits of dancing and walks in the woods and "cosmic" swims as ways to still one's mind.