I did the same thing - albeit too late - took a rock in a 2 month-old radiator after a long road trip (luckily it was only an hour from my house)....errrr. Limped home and jammed some epoxy in the hole. So far so good. I can't tell if it vibrates - I didn't tie it to the center strut. I just used the 4 bolts for the AC condenser like you did.
It's interesting to note that the 60 series land cruisers (non USA) that didn't get AC (no condenser in front of radiator) didn't have any additional protection for the radiator. It's was just the same plastic grill we all have - then radiator.
UPS trucks and most long haul trucks don't install protective mesh in front of the radiator. I went down this road once too (whether to install a protective mesh or not, since I had removed my condenser and got a new radiator) and the conclusion I came to after examining tons of new trucks & cars and noting what Toyota did with non AC cruisers was that it wasn't "necessary" nor recommended. The chance of a rock strike that could damage the radiator to the point of breaking a cooling tube was extremely unlikely. Not impossible obviously, but extremely rare.
Some metal grating (mesh) suppliers will provide wire size to air space specs for the mesh they sell. I was astonished how much air these meshes can block. Typically is about 20% up to 50% depending on the mesh size. That equates to a 20% smaller (or more) radiator. The mesh shown in the picture above is blocking significant air flowing to the radiator (though less than an AC condenser).
The AC condenser has an air gap around all the sides that the air can flow by (if the condenser plugged). The way that the mesh is installed in the picture above, it completely seals off the radiator. All air has to flow through the mesh. Not ideal.
If a protective mesh is wanted for some reason, it would be better to make a simple frame that is a little smaller than the opening going to the radiator so that air can flow around the sides of it too. Don't seal it off.