I agreed with you, until I actualloy went and looked up the definition of "paradox." Basically, a paradox is a self-contradiction (www.onelook.com). I looked in several dictionaries and they all basically said that. Being in the same time period at two different ages is aa self-contradiction.
If you assume that time is absolutely linear, then you have a case that it is a contradiction. However, by the mere fact that there is time travel in the Lostverse, calling it "absolutely linear" cannot be true.
If you assume that Lostverse time is two dimensional, then nothing precludes a person from existing in the same timeframe at two different points in their life. So far, I don't think anything we've learned has contradicted a two-dimensional time theory.
"Shadow," you begin, " Daniel said that time is like a street..."
Yes, that is true, the
perception of the passage of time to the Lostversians is like a street, but their perception is merely the projection of movement in space time along the "time" axis (the 'x' axis in my graph).
There is a
video of Carl Sagan explaining "Flatland" and the perception of dimension when you project from a greater the lesser dimension ... in the case of Flatland, how a 3 dimensional object is perceived in a 2d world.
By the same token, valid movement within a 2d plane projected onto a single dimension might make such movement appear as non-valid to those "stuck" in that one dimension.
Then again, I am just as likely to be completely wrong.