I would like to state that context matters very much here, and I think that this blanket statement, while valid in many instances, is not so here. Let me explain and I’d like to see how you reply.
In a court of law, many lines of evidence can be put forth that suggest that Person A murdered Person B. As each line is reviewed, a determination can be made as to whether or not the individual line is compelling and convicting. Say for instance that three lines of evidence are put forth, and none of these lines are convincing. Person A is still considered to be innocent at this point. A fourth line of evidence is put forth and it is both compelling and convicting. It is now easy to see that Person A has murdered Person B. In this kind of situation, the context allows for the tables to be flipped in the way that you suggest, but it is due to the fact that while one appears to be innocent, there exists the possibility of guilt. Guilt is always a possibility in this context. A single instance of a lack of innocence can turn the tables completely.
In this conversation (above), you are discussing the age of objects. You are asserting that these objects are very young. Others are asserting that they are much, much older. To say, as you have, that one instance can similarly turn the tables is not true because of the context of the conversation. If you have one single instance of something shown to be young, oldness (age) is not precluded. Age is a scale and determined ages are datapoints. We take datapoints and apply trendlines to see where consistencies exist and how strong they are. Outliers do not falsify this kind of analysis at all. Especially one out of a hundred, as you assert.
To take this further, when the earth is found to be very old (4.5 billion years old), everything within it is either very young or very old. So, encountering things that are young says nothing about the overall age of the earth. In fact, it is only when one asserts the Young Earth position is this the case. If one does so, they are asserting that the earth, and everything on it, must be 10,000 years old or less, for instance. So, in this case, you (ironically) are correct. Finding something that is a billion years old, for instance, does falsify the YE position.