I wrote a plugin bb-fix-stop-spam that I am testing. I have not submitted it to the wordpress repository because I am still testing it.
If anyone has bbPress and wants to check if it works it is at:
click on bb-fix-stop-spam to download the plugin. Install it by unzipping it and copying to your plugins directory in WordPress.
If you get the "slow down" error, you might try setting the throttle time to -1 and retry. I did this and then set it back to 10 and it started working, which I am not sure about.
I think this fixes the problem with bbPress and if I get confirmation that it works, I will release it to the world.