There is nothing in the universe that lacks an explanation and that would be explained if stegosauruses exist today.
In the case of God, there are many things that have no explanation , that that could be explained if God exists. … (the fine tuning of the universe would be an example)
If we ever find say a fresh stegosaurus bone, it would be reasonable to conclude that stegosauruses are still alive………………. No body would say “ohhh that’s a stegosaurus of the gaps argumnet” just because we don’t know how the fresh bones got there that doesn’t mean that there are living stegosaurus today. ,,,,,,,,,,,,,, maybe there is an unknown natural mechanism that makes the bones look young , when in reality they are millions of years old.
My point (and relevant to the OP) is that even though the burden proof is on the guy who claims that there are living stegosaurus today , once the evidence is presented, (fresh bones for example) the skeptic is expected to interact with the evidence and refute it. …………….. it would be silly to say “no no no , first you have to disprove all possible explanations, (including all unknown natural mechanisms) and only then you can propose your “stegosaurus theory”
In other words the skeptic is expected to refute say the” FT argument for the existence of God”, ether by disproving one of the premises, or by showing that the conclusion doesn’t follow , or by providing a better alternative.