Rather than fight your security team or do their job I suggest you turn on your firewall and block all traffic, and ask them to rescan. That should fix their bad detection problem. Unless you’re running docker or another actual Linux VM, their fingerprint detection is incorrect or the scan isn’t of your machine. I would even offer to connect to their network with VPN so they can be sure they are scanning your hardware directly and not some NAT device or router between you and them.
Also, don’t blame security too hard - this security theater happens in most organizations. They likely didn’t even bother to check your network address and could be blaming you for the last person to be assigned that DHCP address on your network. They are likely as under funded, over worked as you are. However, security is something you’d hate to not do your part so engage them to be sure they are correctly mitigating the threats they received - if it’s not you, they need to focus their efforts eleswhere as something they scanned needs patching.
Also, if they continue to pester you, figure out how much you value your time and buy this firewall so you can confirm they are scanning your device.
I think just running little snitch is one of the most effective deterrents in a corporate setting as much malware checks for it. They won’t even install or run since they don’t want to get caught by the snitch.