What are you, like 80?
It's not the years, honey, it's the mileage.
The rules (p. 3) clearly say to place it in your floor line:
If you are the first player in this round to pick tiles from the center of the table, also take the starting player marker and place it onto the leftmost free space of your floor line.
The example right next to that shows a player taking the starting player marker and placing it on a floor space. And a scoring example on p. 5 shows a player getting negative points for tiles AND the starting player marker in his floor line...
So, no, I don't see any reason for confusion.