The former Australia rugby international remained standing on Sunday as other players and match officials "took a knee" at the Headingley ground in Leeds, England in support of the Black Lives Matter campaign.
"As a group of players and coaching staff, we spoke about it in depth and as a club we are completely against racism and all for equal opportunity," McNamara told reporters.
"But there were some players and staff who made the decision not to take the knee.
"That was based on personal choice, they have their own reasons for doing that, and we decided we would respect anyone's personal choice on the matter."
The knee protest was popularised by San Francisco 49ers quarterback Colin Kaepernick in 2016 and gained considerable steam following the death of George Floyd, a black man who died in police custody in Minneapolis in May this year.
An empty stand at Headingley was draped in a huge banner backing the campaign, which has triggered demonstrations of support at a raft of sporting events around the world.
Folau, a fundamentalist Christian, joined the Dragons after being sacked by Rugby Australia last year for a social media post they considered homophobic and thus in breach of their inclusion policies.
Champions St Helens won the match 34-6 behind closed doors to resume the Super League season, which was interrupted in March by the new coronavirus outbreak.
The league will continue with 11 teams this season after the Canada-based Toronto Wolfpack withdrew because of financial challenges caused by the Covid-19 pandemic.
