I did not read your other post, but one of my first questions is has he been looked at by the dentist? I feel it is very valuable to have a 2 yr old's mouth checked for dental issues before you start the bitting up process, because it may contribute to a behavioral problem.
I myself am not entirely worried if a 2 year old plays with the bit. After all, they are two years old. I cut 'em some slack at that age.
My bit of choice is a smooth mouth O-ring snaffle, with one break. Although I do often also use a 3-piece mouthpiece with a center roller for more flexion.
I most certainly would NOT stick him in a curb bit of any sort yet.
Also, have you tried adjusting the tightness of the bit to see if that makes a difference? (making the bridle tighter or looser and adjust how many wrinkles you see on the corner of his mouth)
Are you sure the width of the bit matches up to his mouth size? Using a bit that is too small or too large for him can make a difference.
Also, is he responding to your cues to give to the bit? If not, you may not have your timing down quite perfect. I will allow a youngster to chew on the bit (again, cuttingn them some slack in the beginning) as long as they still pay attention to what I am asking. If you need to keep your sessions shorter for his attention span, then keep them shorter. Every horse has a different mentality and a different attention span. Some 2 year olds aren't mature enough to start riding, either. You need to take that into consideration too.
And I just want to make a comment on the biting. It really shouldn't take long at all to fix a biting habit, IF you are getting your timing correct. For my horses, any bite or nip results in one hard slap or punch to the nose, along with a firm verbal NO! They get this reprimand immediately, and then I go back to what I was doing in the first place. You've got to correct them for their behavior within 3 seconds or they will not make the connection. In addition, lots of ground work is key because you need to get your horse to respect your authority and that you are the leader that makes the choices. My horses might try one bite every 4 or 5 months, and they get the same punishment. They know better. But they're a horse, trying to see if they can get away with it.
∞•*˚ Βгįťţαňγ ˚*•∞
It is not enough to know how to ride; one must know how to fall.