The output of the sync stripper in that cable is directly connected to pin 20 so the voltage will be much too high for the OSSC and other SCART equipment.
You can move the sync wire to pin 20 but the output of the sync stripper will still be connected also. I don’t know if that will cause any issues even though it wouldn’t have any input anymore. The safest way is to move the wire and also either lift the sync stripper output pin or cut the trace going to pin 20.
For the best quality video its recommended to buy a new fully shielded cable without sync stripper. If you got the component cable thats in the eBay listing you can also use that with the OSSC.