It's a minor issue, but strictly speaking, yes, the age should be edited out of the question because it is irrelevant. As you said, the only reason we might care about it is that it gives answerers a very rough guide as to what kind of answer the asker may be looking for, but it's better to express that as something like
I'm looking for an answer that assumes zero prior knowledge of physics.
I'm looking for an intuitive explanation, not a mathematical proof.
or so on.
There is a broader issue to consider here: to what extent can askers expect answers at a specific level of expertise? In cases like this specifically, should people with zero prior knowledge of physics be able to expect that they will get answers suited to them? I think this is better discussed in a separate topic, perhaps in chat, so I won't get into it here, but it does have some bearing on the relevance of an asker's age. If we were to decide (for example) that askers do not get to dictate what level the answers to their questions should be at, and answers at all levels of sophistication are fair game, then clearly an asker's age and other qualifications are completely irrelevant, whereas if we decided that answers should be targeted at the level of the asker, it does make sense to have some information about their qualifications in the question.
I'm going to edit out the age right now - someone can revert the edit if we decide it should be in there.