If you wish to submit a potential threat, you can do so directly through the SAS interface. Simply click on System Tools from the main window, then select "Submit Malware Samples". You can then either drag & drop the sample into the box, or use the "+" sign to upload it that way.
As for Sourceforge, they used to be one of the few sites that did not bundle malware/junkware/riskware/adware with their software; however, since they were bought out, they've changed their tune. According to the "How to Geek" blog, they've found that Sourceforge has been taking over older accounts that are inactive and using them to peddle their pay-per-install malware. You can read more about it here: http://www.howtogeek.com/218764/warning-don%E2%80%99t-download-software-from-sourceforge-if-you-can-help-it/
While we always recommend downloading directly from the software publisher, and avoiding third-party hosts such as Sourceforge/Tucows/Download.com/FileHippo, sometimes its not possible. We work diligently to ensure our detection definitions are up to date; however, new threats and variants of existing threats are published on an almost daily basis. If there is something you're not sure about, the easiest way to submit the sample to us is through the above mentioned method.
SUPERAntiSpyware Malware Research and Customer Support