Although Tang Yunhang stayed neutral in politics, there were people who still tried to convince him to join them. Coercion and bribery were just common ways of drawing someone over to their side. Sometimes, they would slap you at first before they gave you a candy.
In other words, they would cause you trouble or scheme against you at first, then gave you a helping hand when you were in danger. Of course, they would hide their real identities when they dealt with you. Since they helped you, you owed them a favor.
Luckily, Tang Yunhang was an upright man who always acted according to the rules, so he gave nobody any ammunition. In addition, he had the Tang family's support, so coercion and bribery didn't work for him.