Atlan didn't think that he would be offered to join them. There was a 4-stage difference between them, after all.
Of course, Atlan had multiple LifeSkills in the 4th stage or below. It was enough to add up the strength that equaled that of 6th-stage Saviors. But they didn't know that.
Even though they were rude, her teammates only told the truth. In normal circumstances, inviting a Savior four stages below the accepted difficulty level was far from what would be considered safe. Not to mention the fact Atlan had only been in one mission, he was completely unqualified to even go to a mission one stage above his level, much more four.
"Don't sell yourself short, Star Porter. You've already faced stronger opponents than us and lived to tell the tale."