Islam has nothing to do with the issue at hand, which is why it is being dismissed. It's perfectly reasonable to want to discuss a particular instance of ignorance ("the Confederate flag is a symbol of southern pride, nothing more"
is ignorance, and quite literally white-washes the history associated with the symbol), without bringing into question the handling of other injustices, e.g. the treatment of women in Islamic cultures. If every discussion about every topic had to include every possible similar scenario, then humanity would achieve very little.
https://en.wikipedia.org/wiki/Fallacy_of_relative_privation
The American flag does probably mean oppression and injustice for certain groups of people, both within the States and outside the States. The collective "we" could probably do better about how we reflect on those past injustices so as to do better in the future.
The more I read your arguments, the more I feel that you are cornering yourself into the position that you are trying to argue against. The symbol of the swastika can have many meanings, and context has not been collectively forgotten: if it's spray-painted on a synagogue in the West by some angsty teenager, but has the orientation of the Buddhist peace symbol, is anyone really going to think that the kid was promoting world peace? Of course not. If the symbol's painted on a truck for good luck on a food delivery guy's rickshaw in some Indian city, is any visiting Westerner going to think that he's a Neo-Nazi? No.
The closest comparison that I can draw between the swastika and the continued flying of the Confederate flag would be if some non-Hindu or Jainist in Germany tried to pass off their use of the swastika on their car as a good luck token. That's a slap in the face to anyone (or their descendants) that had to deal with the atrocities promoted by the Third Reich. That's what the continued flying of the Confederate flag amounts to: a slap in the face to those impacted by slavery and the culture surrounding slavery. You're attempting to argue that the context surrounding the Confederate flag doesn't actually exist anymore. The legacy of slavery (and its incipient inequalities) still exists to this day, so I find it quite a stretch to say that "the Confederate flag is no longer a symbol of slavery." Who are any of us to individually decide whether or not it is still a symbol of slavery? I'm hard pressed to see it as a neutral symbol, when as recently as 60 years ago, legislators and citizens alike were passing it off as a cultural "homage" during the battle against integration. [1] There's not much of a slippery slope argument to be made here: we aren't talking about one or two people that are offended or impacted, we're talking about an entire socio-/ethno-/econo-demographic that wouldn't exist were the institution of slavery extinguished in a just manner. The flag is as plain a symbol as any for 1. the institution of slavery, 2. the socio-cultural romanticism of the "Lost Cause" of the South, 3. the legacy of Jim Crow laws into the present day, and, 4. the continued inequalities faced by African-Americans at the short end of the stick of the previous three.
[1] (bottom of PDF pg. 33) https://web.archive.org/web/20141204200939/http://www.senate...
EDIT: Do I think the Confederate flag should be removed from historical video games? No. Do I think it should be removed from any and all state offices? Yes. White-washing descriptions of history for the sake of hurt feelings is silly, but disallowing the adoration of symbols of cruelty and inequality promotes good nation building and the integration of communities.