The man and his wife recognized him as this. So, his priority is his young master's safety and not anyone else's, or everyone's. Thus, the guard would not leave his young master's side to inquire about the situation and would just focus on his young master's safety. Furthermore, it is not known yet the guard's strength. Thus, it is unnecessary for Qiu Si to leave the carriage and disguise as the thief.
"Let's adopt a wait-and-see attitude." Meng Xing told Qiu Si, as well as the couple.
The couple doesn't know why would Meng Xing decide it like this, but because of what happened just now, they didn't say anything. Furthermore, their lives are in Meng Xing and Qiu Si's hands and they are afraid to offend them if they ask.
"Don't worry." Meng Xing spoke. "Maybe someone will come to save us." He said as his eyes narrowed.