The PTC has a higher resistance than a fuse, and as well it never really goes open circuit, just goes high resistance to limit the current to some value not as high to the short circuit current. As well it will not operate properly with over a certain applied voltage, and might fail as a short with excessive dissipation, or will arc over and allow unlimited current to flow. A fuse has good repeatable performance, low resistance in the working state, and it is effectively an open circuit when faulted and capable of breaking a very high fault current.
Usable if the meter is never used to measure over the SELV limits of 50V and no more than 10A even into a short circuit, as otherwise the PTC can fail with destructive results.