Short version: Before yours breaks off like mine did due to normal age and heat shrinkage, undo the outer-most fastener at each end of the radiator cover.
On my 01 CL-S at 115k I had been keeping this plastic radiator cover trim (official term?) fairly well treated with Meguiar's over the past 12 years, but it shrunk enough that it stressed the left-most mounting hole, and cracked clean across the hole. (So clean I don't really notice it's there.) Then I found the right-most pin also hung against the hole and stressing it there, so I pulled that fastener and stuck it in behind the radiator cover. Looks OK.
On my 01 CL-S at 115k I had been keeping this plastic radiator cover trim (official term?) fairly well treated with Meguiar's over the past 12 years, but it shrunk enough that it stressed the left-most mounting hole, and cracked clean across the hole. (So clean I don't really notice it's there.) Then I found the right-most pin also hung against the hole and stressing it there, so I pulled that fastener and stuck it in behind the radiator cover. Looks OK.