The snoot would be too long to serve as a protective cap/flashtube cocoon.
The tube protector might just work as a storage container with an additional cap:
The additional cap might come with a foam insert to hold the flashtube in place though that probably isn't necessary. Unfortunately, I do not have a spare snoot cap on hand.
The snoot concept would have to be telelscopic, just a longer cap that slides up and down the tube to make the extra length when its a snoot. I'll make one up later.
For the regular container, if you put the bulb in the other way, then you can have the same cap on the other end, it just needs a small spacer ring that fits around the outside of the pins stopping the cap from going on to far. That ring could be made of rubber or plastic or anything. A disk of rubber or dense foam with 4 holes for the pins would be ideal, so you press the bulb pins into the end cap, and then place the bulb and cap into the tube.
Or they make a second cap with a step so it can't go on too far. In the case of making any new caps I'd go with the telescopic snoot.