You all should listen to this guy.
A top kill is DANGEROUS.
The BOP wasn't designed to have a sustained flow like this in it, and there is A LOT of sand in what is flowing out. This erodes it. It could have suffered massive damage during the original accident. A top kill is going to put a lot of strain on the BOP.
It isn't something that you do lightly. It isn't something you do without a lot of planning. If it doesn't work, at best, you've still got shit flowing out at a high rate. At worst, the BOP goes, and 100,000 barrels a day becomes a relatively tiny amount.