The unknown Belgian had replaced popular boss and Chris Powell within hours of the club legend's sacking on Tuesday.
Powell had fallen out with owner Roland Duchatelet over the club's recruitment policy, namely that of almost exclusively bringing in players on loan from Standard Liege and other clubs he is involved with.
But 56-year-old Riga, a former Standard coach, has no such qualms and recalled two of those players, Astrit Ajdarevic and Reza Ghoochannejhad, for his first match.
Riga got a predictably lukewarm reception from the Valley faithful, who then clapped and sang for Powell when three minutes - his shirt number as a player - came up on the clock.
But following a stalemate which keeps Charlton bottom of the Championship, Riga said: "That's the story of football, it's nothing new. I have so much respect for the ex-manager but it's football.
"The reaction from the crowd for my players was the most important thing. I am not here for me, I am here for Charlton.
"Often when something is new people suspect it, but I will just focus on my qualities."
Riga, who has yet to sign a contract, unconvincingly claimed he had only heard about the Charlton job two days ago.
"Don't believe it was something that was prepared," he added. "I know the president and I know what I can do."
He also added that he was "not interested about that" when asked if he was under pressure to pick the loan players.
Riga was flanked by coach Alex Dyer, who admitted the last few days had been "surreal" following the sacking of his friend Powell.
He added: "The players were upset, he was their gaffer, he brought them here. But they understand they are professional footballers and have to play the game to the best of their abilities.
"It's been difficult, Chris has been my mate for 25-30 years. But I spoke to him today and he told me to carry on doing my job."
Yet despite the upheaval Charlton, loan players and all, put in an encouraging display against mid-table Town.
Ajdarevic and Ghoochannejhad were lively throughout but spurned good chances, as did Marvin Sordell when twice clean through in the second half.
Huddersfield, meanwhile, were restricted to long-range efforts until Nahki Wells rounded goalkeeper Ben Hamer but his effort was hacked off the line.
Manager Mark Robins said: "It wasn't a game for the purists but we were good value for the point.
"We battled and worked hard and gave our fantastic away support something to cheer.
"It was a tough environment to play football in and I am very pleased with the clean sheet."