Although it has never come up (to my knowledge) in one of our limited events; what is the official rule for including Reserves, Reinforcements (and now carbonite) in an official DCI-sanctioned sealed event?

You only get what is in your boosters. If you can bring in something else from what didnt make it in your squad (or non-uniques that were killed) then you can, but there are no outside pieces that you can use.

That was my assumption, but they state:

It does not discuss later additions to your squad outside of initial Squad Construction. I believe that what you state is the intent (since that is the assumption behind sealed/draft), but knowing that there are rules in the game that may appear to violate this restriction, you would think a single-line clarifier wouldn't be too hard to insert: "No miniatures may be used outside of the product provided." Especially since their official, 150pt DCI-sanctioned release tournament already violates the above-quoted rule

By the way, I can't wait to pull Han Carbonite and Kazdan as my rares in the sealed!!!

Well, the 120 pt DCI-sanctioned events for A&E release violated the rules too, AND didn't fit with any of the DCI sanctioned point levels, lol. Any time we've done Release events, we've always treated it just like Sithdragon said. With BH, if someone was playing Talon and rolled an 11 for Reserves, then they could bring in up to 20 points chosen from Fringe pieces that had either already been killed or weren't included in the squad to start with, as long as they originally came out of one of your two boosters.

So how many pieces won't be worth fielding since they can't bring anything in?

Carbonite
Ozzel
Kazdan
Garm

am I missing anything?

They're like Spirit Obi in A&E. If you pull one of them you have to hope you get something to go with them. Now the double Han pull to do a half point Hoth Han is probably a longshot, but I could see somebody using Ozzel and being able to bring in something if they get Reverves.

I know if I pull Garm and anything with multiple attacks I'll probably play them together. There's enough Rebel stuff in the set that I'll probably be able to manage 30 points for his reinforcements.

Ozzel, Kazdan, and Garm I think will all have a decent chance of seeing play. Han Carbonite will only get played if you're lucky enough to pull Han of Hoth in your other booster, which is a long shot. Kazdan is good in his own right, but his Droid reserves will only work if you pull a Junk Golem in one of your 2 boosters. Not too bad of a chance of that happeening though, so that should be a decent combo.

I think Garm and Ozzel will almost certainly get to use their abilities since there are plenty of Rebel and Imperial pieces in the set. Everyone will probably pull at least a couple non-Unique Rebel and Imperial figures in your boosters. Plus, all of the Rebel non-Uniques are 26 points or less (bring in the Golan Arms as Reinforcements! Woah, hadn't seen that before now!). On the Imperial side, only the TIE Crawler, AT-ST, and Gotal Assassin are over 20 points. So, I think those will probably be very useable.

I counted them up when I posted and Imps had 9 pieces that worked while Rebel has 11. You might not get an even 20 or 30, but you should have something to use with them if you get Ozzel/Garm as one of your rares.