The premiership defender reportedly took offence to graffiti on a photograph inside the clubrooms, claiming it was homophobic.
It's believed Lumumba brought up the matter with coach Nathan Buckley.
Jason Bell, an openly gay Australian Rules footballer, described the words as casual but offensive homophobia.
"Making it as if it's a joke to be gay and to someone who is gay, particularly struggling to come to terms with who they are or are in the closet as any AFL footballer would be, that could actually be quite damaging," he told SBS.
Speaking on breakfast radio, Collingwood Football Club president Eddie Maguire played down the incident.
"You know one of those things where you get outraged when you see something and others don't know what you're talking about? It's one of those situations - no problem," he said.
Lumumba has previously taken offence to a teammate's nickname that he believed had a homosexual connotation.
Collingwood has confirmed the incident prompted a senior figure within the football department to remind the playing group that postings and messages can be interpreted differently.
The club has declined to specifically condemn the content of the message to which Lumumba took offence.
Ball says that's not good enough.
"To not come out explicitly and not and condone this casual homophobia as being problematic is just as problematic as the homophobia itself," he says.
Lumumba's manager Ben Niall says the incident is a "side-bar issue" in his client's discussions with the club.
"Heritier and the club have had some issues and yes a bit of history there and now it is coming to the point where he is contracted for next year but both parties will decide whether it is best for Heretier to be there next year," Niall said in a statement.
"Both parties are going to spend some time thinking about what they do from here.
"Do they both decide they can work through this or is it time to go their own way and maybe he has to move to a new club?
"Heritier loves Collingwood and respects Nathan Buckley and he acknowledges that the way he expresses himself at times can be problematic and he needs to modify how he expresses himself going forward whether that is at Collingwood or at another club."
The premiership defender has been unofficially linked to the Melbourne Demons.
