Usually the numbers of bounties reward is small amount it is around 1% up to 5% max of total token supply, it is not enough for bounties hunters to dumping their coins on the market. I don't think it will gives bad affect to the price of token, so there are no reason for locking bounties reward after the ICOs end.
all of it could have been. Indeed the numbers are just a little on hold by the bounty hunter, but when a small amount is sold all together will surely cause a decline in the market. Moreover, if the market has not yet formed a strong buy. This is common on the new token is listed on the Exchange.