Concerning “chochams odom’ and his note about ‘acher’. the gemoro is actually in chagigah 14B. The gemoro does say “zemer jevoni lo possak mipumeh” but if you look in rashi , it had little to do with the fact that it was a “zemer jevoni” but everything to do with the fact that it was after the churbon and music was not allowed. Intriguingly, rashi’s “girsa” (actual version) is “zemer jevoni lo possak MIBEISEI”-from his house ! which, of course, would explain rashi’s explanation of not having music after the churbon.
The gemoro-incidentally- continues and says that ‘acher’ had “sifre jevonim ” that he read during the bais hamedrash sessions and this is what took him off tradition. if my memory serves me right- the gemoro also says that he saw a man fall from the tree and die after having being “meka’im” the mizva of “shiluach hakan”, which goes counter the reward for tha mitzvah which is ‘arichus jomim” When he saw that the reward for the mitxvah was not effected (the man died on the spot) he rejected everything.