With the current version unfortunately there is no workaround - the good news however, is that in the next update, this problem will be fixed.
The reason for this behavior is that the MOSS has a filter that searches the content and remove "bad" tags like <scripts> <iframe> etc. Unfortunately we don't have access to this filter and we don't know all the tags that it searches for. That is why we need to "face the problem" first and then add the tag in our list so we can encode it.
Let us know if you face any other problems like this under MOSS. This will help us to find and fix them before the next update.
the Telerik team