For traditional Chinese medicine practitioners, stopping bleeding with silver needles is actually just a routine operation, and Gao Guang knew about these things, but he didn't realize how rare Lin Nianzu's expertise was, so he wasn't particularly surprised.
As a doctor, Carlos was aware of TCM's existence and knew some of its characteristics, but his lack of deep understanding meant that although he was very puzzled and doubtful about the effectiveness when Lin Nianzu began the acupuncture, he was at least willing to judge based on the results.
Therefore, Carlos did not try to stop Lin Nianzu verbally, nor did he exhibit the common tropes of first disparaging or angrily scolding Lin Nianzu, only to end up extremely shocked and admiring the magic of Chinese medicine after Lin's skilled acupuncture significantly slowed the bleeding of the internal organs.
In essence, it was just skipping the part where his face would be slapped; Lin Nianzu succeeded in showing off directly.