The former Wales international Gareth Thomas has joined the vocal criticism of Catalans Dragons’ controversial decision to sign Israel Folau. The 30-year-old dual-code international joined the French Super League club on Tuesday having not played since being sacked by Rugby Australia last May for making homophobic comments on social media.

Thomas, himself a former dual-code international but who made his name in rugby union, is openly gay and said he will refuse to watch any matches involving the Australian.

“So Folau has joined the @SuperLeague. Really upset by this as the game, players, and fans were so good to me,” tweeted Thomas, who had an 18-month stint in rugby league. “All I hope is that as much as Folau wanted his right to speak, then players and fans alike are aloud [sic] their right to respond. I will never watch him.”

The game’s only openly gay player, the former Wakefield forward Keegan Hirst, told BBC Radio 5 live. “Rugby league champions itself on being tolerant, inclusive and diverse and people work really hard promoting those values and this signing and the lack of being able to stop it by the RFL and Super League is a slap in the face to all those people’s hard work. Anyone who has a moral compass or values, this is alienating and undermining those people.”

His views contrast sharply with those of the Catalans Dragons chairman, Bernard Guasch, who has hailed Folau’s signing as a major “coup” and believes the Australian can become a role model for youngsters in the game.

Guasch told local newspaper L’Independente: “When the moods of each other [side] have subsided, we will judge that this player is perhaps the biggest coup in the history of this sport and of [the club] in France. We will then savour the exemplary player he is. I know he will delight the Catalan public. We do not share or tolerate his opinions and we are totally committed to making our club and our sport open and welcoming to everyone.”

The signing has caused a storm, with the Super League executive chairman, Robert Elstone, condemning the move and Wigan declaring their home game against the Catalans in March a “Pride Day” in response.

Folau, who is expected to arrive in Perpignan later this week or early next week, will sit out Saturday’s opening game of the season against Huddersfield but could make his first appearance for Catalans at Wakefield on 9 February, who plan to follow Wigan’s lead.

Wakefield’s chief executive, Michael Carter, revealed he was approached by fans wanting to bring flags to the game within minutes of Folau’s signing being announced, and added: “We’ll have some news next week on something that will be encompassed within our round two game.”

Folau, who said on social media that “hell awaits” gay people, played for Melbourne and Brisbane before switching codes but was told he would not be allowed to return to the NRL.

However, he was not officially banned and the Rugby Football League said it was powerless to prevent the player’s registration, saying the moral responsibility for deciding whether to sign a player sits with individual clubs.

Carter said he was not aware of any of the other Super League clubs being consulted on the matter and would have strongly argued against the move.

“I don’t believe he should have been allowed in,” he said. “Are we seen now as a safety net for anybody who has been kicked out of other competitions? I don’t think it is the sort of advert we should be putting out for our sport. The views he holds are abhorrent and to hide behind religious beliefs is wrong.”

Wigan’s chairman Ian Lenagan admits his club considered the possibility of signing the cross-code player.

“It did cross our mind but we made no approaches,” he told BBC Radio 5 live. “We had filled our salary cap – that’s the reality.”

Wigan’s players will wear rainbow socks and laces for the game against the Dragons in an act Lenagan insists is positive. “We’ve shown we’re proud of our diversity and we’re taking positive action to show we want to be proud of our Pride Day,” said Lenagan, who has already spoken to both Catalans and Stonewall.