No, do not look like it. This looks like plastic. It has to be secured by security bolts which you would need to drill out if you want to replace it.
If you would want to isolate horn from alarm it is doable, but I would need to investigate on diagrams and connectors what to do, but adding a relay would be needed, I think.
Horn buttons go to Pektron box and horn relay is inside Pektron BCU. From BCU wires then go to horns themselves.
You would need to intercept wires from horn before BCU, add relay, take wire from fuse box, connect them all to relay and drive wire from relay to horn, cutting existing one.
What seemed fine then, does not necessarily mean they are fine now.
Maybe to look at boot hinge and wires at that place?