here’s my guess. if someone legit is making a party, why would you think you couldn’t go? If you don’t know you have a question, you don’t ask it, and if you don’t ask him, you won’t know (he made no public admonishments).
If there was a chassidish community and a non-chassidish community and each had lag b’omer activities, or the chassidim had several and the non-chassidim had none, it is possible you may wonder if it is permissible to go to the “other” party. But this is a very small large community and we do things together. When Rabbi Eichenstein makes a party, everyone comes. it’s the only party in town and the lack of party elsewhere is just the norm, i wouldn’t have attributed it to halacha.
I assume there are others who don’t go, and it is possible that if one asked a shaila, they would be told they could take the kids so they don’t feel isolated.
in the end tho, i dont really get it.