I think maybe the rationale for 3 months is as a form of safety mechanism, if there is a sheep-mentality event (ie. everyone panics), the damage is contained, and there is time for people to cool-off.
This is anti free market. In such event you need to let the market play out, risky periods is actually when traders make the most money.
The 3 months lock period is an unnecessary barrier to entry. It prevents a lot of people from investing and playing the curation game. Nobody want their money locked, even a week is too long but it is required to prevent double voting. A week is enough to contain damage anyway, you don't need 3 months for that.
I was just trying to play devils advocate. I think the arguments you've laid out for 1 week are very appealing, I would love to hear @dantheman's take on it.