For telling the truth....
Basically he said that he believed the UK could have a brighter future outside of the EU. However as the BCC has a majority of companies who aren't interested in a brighter future, but more an easier life, he was suspended for breaching their "no official position" stance.
Whilst I understand that a person of that level can't have a "personal" position, I also find that the muzzling of anyone who believes that our future would be better our of the EU is damaging to the whole debate.
If the UK is NOT better off outside, then come to the table and tell us why it is better to stay in. Don't tell us that it's all going to be bad and evil if we leave, that's FUD. Fear Uncertainty and Doubt. It's how politicians win elections and it's business as usual for them.