Your link does not back up your claim that heckling is illegal. In none of the cases mentioned in that article is heckling found to be illegal.
https://nefac.org/is-heckling-a-speaker-a-crime/
https://www.aclumich.org/en/cases/hecklers-veto
https://stanfordmag.org/contents/the-first-amendment-does-no....