Nothing to warn about.
"… or Else"
Jo understood subconsciously that going in that pyramid and rescuing Sora was not his task. It was not what the group and its leader needed right now.
He and Ikkakumon would provide a needed distraction, risking a direct confrontation with Etemon and his forces. That would enable Taichi and Koushiro to start their rescue operation.
Taichi had to get her back, regardless of the risk. Jo was not even able to imagine how he would react if Taichi failed, but the mere idea terrified him to his core.
Taichi had to get Sora back.
He had to get her back.