This was fixed in ISL Light Desktop plugin for Windows 1.4.7 (2013-11-29). When remote desktop streaming starts either client or operator can now disable shared clipboard. Streaming side can find the setting by right clicking on the revoke control and find the menu Clipboard sharing. Operators can disable clipboard sharing from Tools menu.
Read more here – http://seclists.org/fulldisclosure/2013/Dec/14 and http://www.islonline.com/help/isl-releases-info/any/manual/?2013-11-29-rel-info-isl-light-desktop-plugin-1-4-7-win.htm