Who says you need to double tap anything. You can already swipe up on an iPad. So just make that for all devices. One swipe up, one over and you are in Control Center. If that's too much work for folks they have serious first world problems.
How is that better than just one swipe up though?
And why should we have to invoke the multitasking procedure to get into control centre? It just doesn't make sense.
It's like having to go through messages to get to the phone.. they're completely different and you shouldn't need to go through one to get to the other.