I can't say that I've seen that. What I have seen is that those who push #BlackLivesMatter frequently argue strongly against #AllLivesMatter, showing that to such people #OnlyBlackLivesMatter is much more accurate.
This "question" bears a striking resemblance to today's Dilbert strip. Technically, this is known as a "leading question". It's purpose is not so much to make a query, but to make a claim in the form of a question. The most well known such leading question is, "When did you stop beating your wife?" where the claim being advanced is that the person being questioned beats their wife.
Prejudice: So your prejudice—which exists only in your own head—gets to define reality for everyone? Are you god? I hope you don't cross the street using the same standard you use to judge others. ("Is it safe to cross the street?" "I don't know." "Good. Let's go.") So you're a mind reader? Amazing! Quick, tell me what I'm thinking right now!
So you're claiming they were able to read the mind of the security guy when it has been explicitly stated in various media reports that they were NOT told the reason they were identified as potential thieves? Think about that. They have no direct knowledge of the reason anymore than you or I do. Their claim that it was racism is their own speculation. Such speculation is no more valid than yours or mine. Let me repeat something you yourself just stated. They Do. Not....
Again, how many times must I write "We don't know" before you understand that "We don't know" means We. Do. NOT. Know?!? Based on what passes for "reasonable" and "honest" to you, I would be fully justified in asserting that you are a 4 foot 9 inch woman with flaming red hair who likes baked beans with sauerkraut, and dalmatians, because I don't actually know otherwise.
What makes you think "loud, boisterous" behavior is the measure? If I was planning to steal something, I would think drawing attention to myself would be the last thing I would want to do. Could it be that these guys were the exact opposite, being inconspicuous, which is out of character for most teenage boys, and that's what drew the security guy's attention? Again, we don't know.
Here in the U.S., schools of all levels have implemented school uniforms. I don't know about Australia. Again, we just don't know. And when that perception is false or with no foundation except your own biases? Do you really think it's appropriate to do things like fire someone (as suggested by several people earlier in this thread) or worse based on such perceptions? Is that really the kind of world you want to live in? What if you're the one harmed by such a misperception?
Kudos to them on their behavior when confronted. However, your comment must be modified to say that nothing about their behavior or demeanor that you saw suggests they might steal something. Again, we only see part of the confrontation, and absolutely nothing that occurred before that. It is possible that they were acting suspiciously. We just don't know! You've admitted as much, yet you still attempt to draw conclusions based on ignorance. As for their dress, they appear...