In the Items view, for a single file we have the (customizable) submenu "Open".

In the History list for a single file, we have the "Save this revision as..." command along with "Open" and "Open with...".

For consistency and ease-of-use, the "Open" submenu should be available in the 2D History view for a single file as well. Also, the "Save this revision as..." command should be added to this "Open" submenu.

This is much related to another uservoice that requests adding the "Save this revision as..." command to the "Open" submenu in the Items view as well:

http://plasticscm.uservoice.com/forums/15467-general/suggestions/5125416--save-as-from-browse-repository-on-this-changese