That is the takedown catch and it doesn't lock into the safety; the end of the safety just acts as a pivot pin for it. When the gun is assembled, it is held in by the slide; when the slide is off, it is held by the right grip. The new grip just has to be wide enough to partially cover the catch.
Warning!! In checking this answer, I got out my own gun and found that the original grips had not only warped further (I knew they were bad) but apparently oil had partially dissolved one grip and left a muddy brown crud all over the gun. (That was REALLY BAD plastic!) I am glad you asked your question as I found the trouble and can fix the problem (by throwing away the original grips and either finding some replacements or having them made).
So if you obtained original grips (you indicate the ones you got were already warped), I urge you to consider trashing them or at least keeping an eye on them.
That gun is flat sided, so grips should be easy to make from plain wood as long as you don't want to follow the fancy shape of the originals or have them checkered. Grips for the Unique Kriegsmodel and the French equivalent will fit, but won't retain the takedown catch.