The goalkeeper launched the bottle towards his own supporters on his home debut against Tottenham in October after hearing racial abuse coming from the stands.
No action was taken against the Polish stopper or the supporters involved, but he was promptly dropped by former manager Nigel Adkins and did not return to the side until January.
But Boruc has told the press in his homeland that he does not feel any guilt about the incident.
He said: "I won't say I regret it, because I heard insults from the stands. Racist ones.
"But I blamed myself for it because I gave Adkins the reason that he could sit me on the bench," he added.
The 33-year-old has now established himself as first-choice under new manager Mauricio Pochettino and has won over the Saints fans with a string of good performances, most-notably delighting the support with a crucial last-minute penalty save in the 0-0 draw at Norwich earlier this month.
And Boruc, who confirmed his agent is in negotiations to agree a contract extension, says the experience has been character-building.
"The coach had his vision and I was a bit angry," he said. "But I like such challenges, and feel good when I hit the bottom, because you can start from scratch."