It looks like someone has shortened the sear on either the bolt,,or the trigger sear,,maybe both.
That to allow a shorter & faster striker fall.

The problem is that when the sear engagement points are shortened to gain that speed-lock type of action,,the striker does not sit back as far when at full cock.
That places the notch in the striker out of position that is there to accept the lug on the Safety when swung into place.
The striker knob itself is too far forward to allow the Safety to swing as well.
So even if you grind that seemingly offending 'tab' off of the Safety,,the Safety still won't work as the engagement groove in the striker is too far forward to engage.

Manualy pull the striker back and at the same time attempt to engage the Safety. I'd bet the Safety will glide right into place once the striker is back another 1/4" + or so.

Take the bolt out and examine the underside of it,,the square sear engagement abutment. See if it looks filed or ground on.
Also look at it's parent engagement surface on the trigger mechanism sitting in the bottom of the sear channel in the action. It may have the same look.

If you have another 1903 Greek or a Steyr 1903 Commercial, simple side by side comparison will show any difference quick enough.
They are the same action, minus the bolt hold down spring on the Greek Military action.

Just looking at the pics, the striker on the rifle looks way to far forward for a normal full cock position.

If either has been worked over,,the trigger group part and or the striker are generally available as surplus 1903 Greek M/S parts.