My electronics is a little rusty so wait for confirmation but I think you might damage the driver doing this.

The 2k resistor is there to pull the line high when the phototransistor is off. When it's on, the phototransistor pulls the voltage down to near ground potential.

Without knowing the spec for the phototransistor and relay I can't tell whether the phototransistor is robust enough to cope with the loads a relay would impose. With a 2K resistor there will be around 12 milliamps flowing when the photodiode is conducting. I think the relay would be much more than this and there will also be voltage spikes from the inductance of the coil.

Again, wait for confirmation but I don't think you need a relay - just use the leadshine circuit.