At last the thread is back open so I can tell you.
The writers (in an interview) said that Optimus kills him off.
Well Bay (et al) grew to really like a counter character to the Bee
and no one wanted to see him killed off. The idea goes back many, many years. Chevy vs Ford, etc. Originally Ford said NO cause they didnt wanna be the badguy so they asked Saleen. Steve Saleen said HELZ YEAH!! So the mold was cast.
They all loved him. This in turn led to a decision not to
kill him off. It wasnt that they edited it out....-THEY NEVER EVEN SHOT THE SCENE!
This is documented in the script and trade novels/paperbacks.
Soooo Barricade would be around to harass The Bee on
future episodes.
Well.....Low and behold - along comes #2 and they got different writers who were not told of Barricade's sparing so they take off where we left off and according to the script -he is toast.
Soooooooo that is why he just disappears.
I think this snafu can be used to a great advantage in the next movie
should they chose to do so.
and there you have it!!