Heh, I actually have had a airblast jump plugin written for awhile too. I wrote it before i wrote the code you have linked. the 3-pg servers are running that ab jump plugin now. I came here cause there is a very minor bug in it and i was searching for a wait to fix it. I suspect you might have the same bug as I use Dukehacks also and its somewhat related to that. I shall compare our code and post more about it later if the bug is there.
Edit: nope, i was wrong. You check for the nextattack time so its all good. I overlooked that at first so one could get away with quick switching and jumping without using ammo.