Doesn't that solution mean I would have to activate the game twice - once via SDC on the internet computer and again via email on the games computer? How does that work?
That's fine. If you ever legitimately reach the activation limit you can simply ask support to reset it. Two activations won't even be close to that point, though.
To activate the game on a computer that is not connected, follow these steps:
1) Start the game; you will get a prompt for your serial and email. Provide them and continue.
2) It will fail to activate and ask if you'd like to activate by email. Click Yes.
3) Copy the subject line and big block of letters into a text file, or into your email program, and save it off to portable media (CDR, USB drive, floppy, etc).
4) Take it to a web-connected PC and send an email to activate@stardock.com with that subject line and content.
5) You should receive a reply with a file and some instructions; take the file back to the non-connected PC and you should be set to go.
The only thing that really invalidates an activation is reinstalling windows. Just updating the game won't make any difference to the activation, it'll still be good.