Has anyone had luck using negative reinforcement for bullying?

I have a 2 year old youngster and a 9 year old senior.  The youngster
has too much energy for his own good.  I try to help him burn it off
constructively but sometimes I don't do a good enough job.  He stalks
and attacks the senior.  My poor senior is becoming a bundle of
nerves.  The youngster is a friendly good natured cat and I'm
convinced that the attacks are playful.  The senior doesn't agree.

I'm looking for ways to curb the young guys bullying behaviour.  I
started trying a 2 minute timeout in the bathroom everytime he
attacks. I usually have to chase him around the house to catch him -
which he loves, so it's more positive reinforcement than negative.

I'm hesitant to try the spray bottle approach because he's such a good
natured cat now and I don't want to do anything that could make him
fearful or skittish.

Has anyone successfully dealt with this problem?

Thanks,
Mandy