The defender came back into the Saints team for their Carabao Cup second round clash this midweek.
Bella-Kotchap was involved as the Saints won 5-3 against Cardiff City, with the 22-year-old coming off the bench.
Martin told the Daily Echo: "I think we have five centre-halves, I think he's obviously the sixth one, which is not ideal for him.
"I thought he did great when he came on tonight but I think, hopefully, it's shown the world that he is fine and he's been training, he's fit and he can play.
"Honestly, I'm still so annoyed and angry at that lazy journalism over in Germany and I thought it was lacking context. Nonsensical, actually.
"I'm really furious about it because Armel's fine - so we'll see. He's shown everyone he's fit and he played to a really good level when he came on the pitch.
"We'll see where he ends up as he has got a lot of interest, I'm sure. We'll see."