The T350 doesn't have a locked bootloader and neither does OEM UNLOCK unlock the bootloader on any Samsung device.
Now I understand the OEM Unlock toggle doesn't simply unlock a bootloader and is usually used for factory reset protection.
But the question becomes, why do some devices have the toggle and others don't? My T350 doesn't have the OEM Unlock toggle but my T560 does.
And usually rooting or custom recoveries end up need this option to be on. Or in my case I've seen the two situations automatically turn the toggle on by themselves.