The slave was just a temporary way to solve the current issue, establishing his authority over the dwarves instead of fighting them. Tang Shaoyang wanted to figure out first if these dwarves could be taken out of the tower or not. If they could get out of the tower, then he would bring them with him back to Earth and let them blend into the other dwarves.
"I would rather die than become your slave!" One of the guards reacted strongly and charged toward Tang Shaoyang with the ax.
Tang Shaoyang shook his head and caught the ax with his hand. It was like taking a toy from the kid. He took the ax from the angry dwarf. He then reached the dwarf plate armor, raising the guy to the air before slamming the dwarf to the ground. That silenced the dwarf, who was not dying yet. The dwarf was still breathing, merely passing out from the impact.
"Do you still want to fight? Or do you want to call your leader for my offer?"