The "rules" of an ICO or bounty campaign do not trump the rules of the forum. If you plagiarize, you will be banned.
I think an exception can be made in a minority of cases where the user is obviously a good contributor to the forum, with a history of useful and constructive posts, an extensive positive trading history, huge numbers of good reports, etc., and the plagiarism wasn't made for purely selfish/financial reasons. In these cases, a temporary or signature ban is acceptable. The vast majority of cases do not fall in to this category however, and certainly not the example you have given. People plagiarizing for the sole reason of earning money through a signature or bounty campaign deserve a permanent ban.
I am not sure about it as in this case the user was asked to promote the brand/project by the project itself so he did not claim it as his own content and also mentioned the project's URL which means he posted the content for the company. If he had to post a "Note" below the message that he is posting this content on behalf of the project, would it still be termed as plagiarism? This is similar to posting ANN threads that contains content copied from the website. I couldn't find the source of the message but it was provided by the project itself.