A news report comes out as, "dozens dead at nightclub shooting," and someone posts, "I bet it was a muslim. We need to kick all of them out". The first response is, "We have no idea who was behind this." Or, even worse, maybe even an outright denial if there's some initial evidence that suggests they're not Muslim.
Days later, once more evidence has been collected the police confirm the perpetrator was a Muslim radical. From that point on, every argument against discrimination gets tarred as being apologism and backpeddling. Sound arguments are dismissed merely because they followed after a valid argument that turned out to be unsound. Racism wins the day.
There is absolutely nothing wrong with making more than one argument if we have a good reason to believe each is valid. Just following that pattern does not mean anything about whether it's correct or not.