spyware, called Pegasus

I have an older iMac, ancient by today's standards. It is a Mid 2007 running OS X El Capitan, version 10.11.6

I have been informed that El Capitan is the limit on this machine. I read the article concerning the NSO Spy Group. I have down loaded the fix for my iPhone but since the fix for iMac is OS 11.6 I am unable to update my iMac.

Should I worry or care. Perhaps my device is so old it will not be effected.

Any input is welcome.