A tiny problem

I have a tiny problem, well no Zachary has a huge problem- his brother. Michael is a great brother, he is really interested in his brother, we have only had mild jealously issues, and he seems to genuinely care about Zach's needs... but he is rough. Michael really really wants Zach to be big enough to play, big enough to wrestle, and big enough to race. Zach is learning to support his own head, clearly we are a ways away from playing. Michael likes to have Zach nearby while he plays, he shows him toys, wants him there when we read stories at night, etc. He constantly asks if Zach can sleep in his room, which is ok sometimes now, but will be a huge issue someday because one of them likes to sleep and the other doesn't, I can see zach crying because his brother won't let him sleep... oh wait that happens already. He won't let Zach take a nap, i find him him near the crib, on the bed, or whereever else Zach is sleeping, poking, pinching, bouncing him, whatever it takes to wake him up- poor zach. The limited sleep he is learning to live with (or I am hiding him away), but the wrestling... I know it sounds like i am being dramatic, but let me elaborate. You know those bouncy chairs that vibrate and babies sit in, they have wire legs, yeah michael "hugged" zach yesterday and bent the chair so instead of being slightly suspended zach was flat on the floor... He hugs him as tight as he can and grits his teeth (yes mom he has started gritting his teeth). I know he wants to be with his brother, but how do we reinforce being soft- you know not launching yourself on your tiny brother, or not kneeling on him (sad that we have had that talk), not poking him in the eye, and not squeezing him until he cries. Luckily, Zach is really really patient with him. He's ok with Mikey's slobbery kisses and even ok with the wrestling for a bit, but even he has limits. So how do you reinforce being soft without making him dislike his brother, or think he is too fragile. I want them to be brothers, i want them to wrestle, i just think we should wait until zach is... 6 months old or so. I wondered why Zach was a giant, this is why, a normal sized baby wouldn't be able to withstand the mikey tornado- good thing zach is a big guy.