If you toggle the visibility of either the SIOX tool or of IScissors in the Tools Dialog, the toolbox will adjust itself to contain 5 rows of 6 tools each and each rows tools are related to each other in functionality.
Toggling the visibility of a tool doesn't diable it. It simply makes it so that it is not visible in the tool box. The only problem is picking which one you want to keep handy. For me, it is a no brainer. I don't really use either one but occasionally I try to figure out how this new SIOX tool works.
After changing the tools, I decide to change <Toolbox>/File/Preferences/Toolbox options from the default (which is all toggled off) to what I like (which is all toggled on). GIMP has an impressively large dialog for this: