That is nonsense, your instincts were correct. The sights on eBay have been altered. There is an M14 like front sight that has an identical base and dovetail but with a higher blade. It is the early M79 Grenade Launcher Sight, which I think was used only on the early Springfield M79's.
On the left is the standard M14 sight. Middle is the early M79 sight produced by SA. Right is the later improved M79 sight produced by the other contractors.
The sight blades on the two M79 sights are identical in height, but higher than the M14. All three use the same sight screw too.
People will come up with wild imaginations to sell stuff on eBay.


On the left is the standard M14 sight. Middle is the early M79 sight produced by SA. Right is the later improved M79 sight produced by the other contractors.
The sight blades on the two M79 sights are identical in height, but higher than the M14. All three use the same sight screw too.
People will come up with wild imaginations to sell stuff on eBay.