Horner explains Red Bull silence after Piquet comments
The boos for Verstappen also followed his
comments in the media on Thursday where he condemned Piquet's racially offensive comments in reference to Hamilton, but also insisted Piquet - who is his partner Kelly's father - was "definitely not a racist" and suggested the scandal had been "blown out of proportion".
"Max is absolutely clear that he is fully supportive of Lewis and not just Lewis but any form of racism or discrimination," Horner stressed to Sky Sports F1.
Horner also defended his Red Bull team's response to the Piquet comments.
Red Bull were one of few teams who did not issue a statement or a supportive message to Hamilton when the news broke earlier this week.
But Horner believes the team made their anti-racism stance clear with their action against reserve driver Juri Vips, who has been dropped by Red Bull following racist comments of his own during a gaming stream.
"First of all, of course, we were appalled at Nelson's comments," said Horner.
"It is from an interview from some time ago and obviously we had had an incident with one of our young drivers at the end of last week.
"We took very definitive action when he had made a racist comment and we immediately removed him from the team.
"Then this comes out and we felt we had made a very strong statement through the action of actually dropping Juri from the team and not in any way condoning any form of racism and discrimination.
"We had put out a statement earlier in the day about Juri about having zero tolerance to racism, so to then put out another statement about Nelson Piquet...
"Of course, we are fully behind Lewis, fully signed up to the Hamilton Commission and sometimes actions speak louder than words.