i resently bought a parts car to fix my daily but its in better shape then my daily so ive gotta cut the radiator support out of my daily, is it safe to pop rivet all the spot welds rather then welding. ive seen body shops do this. is it really as safe to do this?

 

Honda used a LOT of spot welds that hold the support on - especially at the front of the frame rails.
If you have enough material to get the support to hang on with rivets then it should work fine.
I had mine on with a few tack welds and no issues.
The bumper supports bolt on so they will help hold down the areas near the frame rails.
More attention should be taken to the areas out by the headlights.