It sound weird to me that a company that has a role to fill will take anyone from "just graduated and can type" to "experienced tech lead". Doesn't sound like a role that is clearly thought out.
If you have stuff for a junior hire to do and stuff for a senior hire to do, and you end up hiring the junior hire, what happens to the "senior" work? Same question if you end up hiring the senior guy.
We work on applied R&D and the seniority boundaries are fuzzy. In practice if we take a junior engineer we can get a senior engineer or two off lab work (who in principle should not be spending any time in the lab, but does a little). If we hire a lead it frees folks doing high level concepts (and powerpoint) for more hands on stuff.
If you have stuff for a junior hire to do and stuff for a senior hire to do, and you end up hiring the junior hire, what happens to the "senior" work? Same question if you end up hiring the senior guy.