The answer is pretty clear. How can you be sure the program is save ? You have to check the source code ! Generally the open source program is safer than the proprietary one, because the source code is available and thousands eyes observe it. Freeware does not necessarily provide the source code. Freeware only tells you that you do not have to pay. The main goal of this article is to mix open source and freeware and spread fierce uncertainty and doubt (FUD). Actually nothing new.

Take a look at http://androidwiki.com/wiki/Introduction_to_Android . In this aspect Apple has to leverage the iPhone as quickly as possible.