That was the crazed Adolfo, a (typically) mad Callas fan. Now, I am no Scotto fan myself, but I do think it was most unfair of him (he was promptly ejected from the house). This all had to do with the rude things Scotto said about Callas in the Zeffirelli documentary, where Scotto tried to play innocent while settling up an old score she had with Callas over Medea. This incensed the Callasiani, and this happened around that time, on the telecast of Luisa Miller.

Leading eventually to the "She clean up the bel canto, I clean up the verismo repertoire" quote, and allegedly di Stefano sending her a feather duster in a florist's box for long-stem roses. (I hope that really happened.) But nobody rode the early wave of opera broadcast on TV like Scotto, and there's always her Met Suor Angelica to silence those who insist she was unworthy.