Suppose Venus really were "young". Suppose it were molten only a few thousand years ago. What would it look like now? Probably about the same, molten. However, we know that Venus is not molten now, because our landers, and Soviet landers, have landed on a solid surface. Furthermore, we know from the extensive topographic relief long since verified by Earth- and spacecraft-based radar, that the crust of Venus is thick. It must be, anywhere from 30 to 70 km thick (Baisukov et al. (1992)), in order to support visible relief. Is it possible for Venus to cool so much, so rapidly, between then and now?
Just as I said, nothing but an assumption; no real measurements or any other basis.