Reread, yeah Bibidi had Buu on earth, but they did know about the "golden fighters" and the BT thats why Yamu and Spopa were sent out. And even then, optimally thats still Goku, Vegeta, Gohan, and Piccolo 10 years on of training post Freeza all rushing Dabura (maybe even Trunks and Goten helping out now). Dabura was outmatched by an out of shape SSJ2 Gohan that Vegeta directly states is worse than when he was vs Cell. Dabura aint winning that rush. Same with Cell only far far worse. No Androids to absorb, + discovery of the subbasment tipping them off once the Time machine is discovered = Imperfect Cell gets folded by a rush of out of the ROSAT Vegeta, Trunks, and Piccolo with Goku and Gohan training for backup.