I wouldn't have thought making the BBB more permeable is a good idea but don't understand enough about this to comment. It seems it would let more toxins in than allow them out. Also presumably most people with mercury toxicity have quite 'leaky' brains anyway....I know I'm quite leaky lol!
Here is a recent post in the Autism/Mercury group which contains several of Andy's posts, including one with comments on the BBB, mercury etc. You need to scroll down to message 1594. It includes the following quote
"The brain is protected by the blood-brain barrier which absolutely
stops certain toxins from passing at all, ever, no matter what. If the BBB
gets leaky and you are really really sick, it is letting maybe 0.1% of the
nasties pass - way too low to let all the mercury out."