What was the problem? Was it the bandwidth costs? AFAIK most of the files you can download from SourceForge are actually not served by SourceForge itself but by mirrors. So those guys are shouldering the brunt of the costs not you. By doing something like this I would not be surprised if some of the mirrors decided they do not want to work with you anymore.
If you wanted the extra revenue by bundling ads with applications you should have done this explicitly with a prior public notification of this being done. For example News.com for a couple of years now bundles their own installer with the downloads they provide. I've seen other places do the same thing. But you should always be able, as a user, to disable the adware installation. Also the user should know before downloading a binary that it has adware in it. Not stealth adding it without people knowing about it. Last but not least hijacking someone else's account for these shenanigans was quite pathetic and fail. This was all handled quite poorly.
A lot of people have been leaving SourceForge as is because it has worse Git integration than other more recent sites and this is just another nail in the coffin.