Multiple Macs Controlled by single USB IR Receiver
Yes, this could be a viable solution. This is commercially known as a IR Repeater system. It would not require any usb, as a microcontroller can read the IR signal, and repeat it to multiple IR transmitters/leds. A google search for "microcontroller IR Repeater" will provide a multitude of projects that you can build off of.

Alternatively, as @MathewHall suggested, if you are on the same network, one of the macs could act as a server to control the other ones. There are applications that can use the same IR remote to launch or control a custom application or script. (from the Apple Stack Exchange). With some basic coding, you can have it done in software, no hardware to make or replace if broken. And easier to expand if needed.