As the OP, let me just remind all that this is exactly the intent of this thread: what should an EMHC do/say when people approach you for a blessing?
The liceity of communion-line blessings, as I have said earlier, is NOT the issue here, simply because communion lines are meant for communion. The reality, however, is that decades of poor or non-existent catechesis have adulterated the purpose of the communion line. Blessings in the communion line, whether from the priest or an EMHC, are woefully poor consolation prizes in lieu of actually receiving Our Lord. And besides, the priest licitly blesses the entire congregation five minutes later at the dismissal.
Back in “the day” when we had good catechesis, every Catholic over the age of seven knew that if one could not receive communion, one was to make a spiritual communion, something along the lines of this (from one’s pew):
ewtn.com/devotionals/prayers/blsac4.htm
So, let’s just all assume (whether you agree with it or not), that communion line blessings are illicit (which they are, as Benedictgal and others have shown). What do you say and do?