This seems quite irresponsible
ET probably has rules about blinding pilots with lasers same as we do. Also surely by the time ET notices the transmission (possibly an eye popping sight) the signal will have passed.
I can't imagine an ET using laser as an interstellar transmission medium though. Apart from the speed-of-light delivery there are far too many things to disrupt and weaken the signal over long distances.
So as above, the only response this is likely to generate is a knock at the door from the interstellar police asking if we can turn off the laser, hand it over, and be forced to listen to vogon poetry for a few hours...