There's no way to disable the Save button on the Adobe Reader "toolbar" - not from DominoPDF or from any other product.
You can just stop someone from re-assembling the PDF contents.
The Save A Copy action in the reader is just like copying the PDF file at the system level with a new name - so there's no definite way to prevent it from happening.
The encryption options you can enable with DominoPDF will stop someone from distilling the PDF to a new copy, printing it, copying text/images etc. but they will typically always have access to the file itself.