The missing "Save Target As..." option in the context menu of the RadButton, set as LinkButton, is encountered on IE and is caused by browser behavior. On the other major browsers this functionality works as expected.
A possible fix would be to override the styles and to set display: inline
to the span by configuring its CSS class rbText
Please keep in mind that it's very likely to cause incorrectly displayed and aligned text in the button with this modification.
I hope the listed information helps.
the Telerik team