I personally would expend less money and effort to make this perfect, simply because it's on plastic rather than metal and therefore will never rust. That doesn't address your question about appearance, but it is a vote for the "see if a pro can touch it up presentably" approach.

 

Considering the available options, that is probably the one that makes the most sense.

If it was a color for which it was easier to match the color, having the bumper refinished might be a viable choice, but, with the atomic silver, even with the paint work being done by a highly skilled paint technician, there is no guarantee that the bumper is going to acceptably match with adjacent panels. As someone who admits to being more than a little OCD about the fits and finishes on my vehicles, I know that, if the color match was only a little off but very close and even if no one else noticed a slight mismatch, every time I walked up to the car, that slight mismatch would catch my eye, and it would bother me.

So, if a "pro" can take a shot at touching up the bumper, even if it isn't perfect, at least the color mismatch would be only in a small area and not one with the entire bumper. Plus, a mismatched spot on the lower portion of the bumper will be less noticeable than would be a color mismatch higher up. And, obviously, a less than perfect touch-up is going to cost a lot less than a less than perfect refinished bumper that has the potential for making things worse rather than better.

Also, this situation can be a learning experience for the OP. Things like this are the reason why, for those who are particular about fits and finishes, they should stay away from colors like the atomic silver. That is why, for me, I've had many non-metallic black vehicles, but, when I've chosen other colors, I've gone with colors like darker grays. They may not be as stunningly beautiful or flashy as a color like the atomic silver, but, at least, I know that, if I need paint repairs, major or minor, it is likely that those repairs will not catch my eye every time I walk up to the vehicle.

 

Apologies, yes PDR is not an option on the bumper. Can see the photo much better on my PC.