I do not understand how locking a bounty thread can even affect anything at all. Reports are sent to the bounty branch, even after the bounty has ended, what prevention of price fall can we talk about ...
LOOOOL, locking the rewards not the bounty thread, bro! 
You gave me a good laugh.
Price of the token won't be affected in any way if their bounty thread is locked, OP meant locking the bounty tokens sent to bounty hunters to prevent a dump because they can't sell for a fixed time after they received their rewards.
I think it was just a confusion, does it make more sense to you now after my explanation?