While Dante did not attach a Celestial Tether between himself and the spiders in order to understand what they were thinking, he actually didn't need to go so far given the body language of the arachnids after he appeared.
Even he himself felt a little bad about what he was doing, for it was a little overboard ethically. However, it would take too long to move about and hunt different D Rank and above monsters in the wild given how they were spread out, so this 'dungeon' was truly the best bet for him.
Of course, Dante didn't plan to take long anyway. He took out his Blood Battle Halberd and attached his recently expanded Blood Qi that had changed its form after it broke through.
