First of all, note that that text was written in June, 2003. Many things have changed since then.
Messenger Plus! never installed spyware, and the sponsor program (which is what is talked about in the article) has always been optional. During installation you are (and were) always asked if you want to install it, and with the more recent versions of Plus! this screen has been made even more clear. For example, compare
this old version to the ones you now see in the installation program
/ 
