Our Gemara on Amud Aleph discusses Rav’s reluctance to teach publicly after drinking even a small amount of wine:

“Rav would not place an interpreter before him, i.e., he would not lecture in public, from the time that he drank wine on one Festival day until the other, the second Festival day, due to drunkenness.”

The Gemara in Kerisus (13b) raises an obvious question: Let Rav teach his lecture, but not issue specific halachic rulings, or even just teach midrashim (Rashi ibid)? The Gemara answers that due to Rav’s stature it was inevitable that people would seek halachic rulings anyway.

Presumably, he was concerned he would be tempted to respond, or perhaps people would read into his remarks matters of practical halachic significance when not so intended.

Rav Soloveitchik (Reshimos Shiurim, Horiyos 2a) notes that the Rambam (Laws of Entering the Mikdash 1:4) has a different slant:

“If he was a sage who delivers rulings on a regular basis, he should not teach, for his teaching itself is a halachic ruling.”

According to the Rambam, for a great sage, it is deeper than a concern that his words will be taken as a psak. His teaching itself constitutes psak, whether he likes it or not.

I find this particularly ironic coming from the Rav, as I personally heard complaints from some of his talmidim that others took his musings and chakiros in shiur as halachic rulings. On the other hand, here is an interesting quote from Rav Herschel Schachter, Shlit”a, that pushes in the other direction—though surely context-dependent:

“I was fortunate to have been in the Rav’s shiur for ten years, from 1957 to 1967. If you paid attention to the shiur, [you realized that] in many, many cases, the Rav was deriving the halachah from the Gemara and stating his halachic opinion.”

(https://jewishaction.com/religion/jewish-law/speaking-with-rav-hershel-schachter/)