How to short two nodes electronically
Take the problem one level up. Do you want to control the SAA3010 (which has been obsolete since eons) with a microcontroller or do you want to send RC5 codes. I guess you want the latter. One of the reasons the SAA3010 is obsolete is that these days about every device contains at least one microcontroller, and microcontrollers can do this task as easily as the SAA3010, including the modulation.
I've never used Arduino, but I guess it can output RC5 codes. If it can't, or if your Arduino doesn't have the resources left, use an external microcontroller which you control through UART. This will probably cost you less than a few of the switches you would use on the switch matrix, so it's definitely the cheapest solution.