If the asset owner holds the entire supply and the asset is not locked, then allow the owner to reset the supply (e.g. set the supply at zero) and change the divisibility status.
Say I launch a crowdsale and promise only 1 million tokens. I create the 1 million tokens and lock the asset. I can “prove” that the asset is locked.
Then I launch the crowdsale. After I receive payment and right before I send the first tokens out, I change the supply to 10 million because I still own all of the tokens.
More Mischief
A more subtle variation on this is to send tokens to 20 different addresses I control. I can see “See the tokens are distributed! I can’t change the supply!” But then I could send them all back to the issuing address and change the supply.
Conclusion
I think locking an asset needs to be permanent. Otherwise there is no real assurance that the issuer can’t change the token in the future.