I think it's pretty safe to say that cards that target the discard pile or its contents are actually supposed to work. I guess the question is, does this work within the technical constraints of the rules, or only by fiat?
If I look at the rules and see that
1. The card requires something impossible to ever function even minimally,
Then
2. Either
a. The card does nothing,
Or
b. The requirement isn't actually impossible,
Or
C. The card doesn't have the requirement, appearances to the contrary.
A's not really an option. The game isn't a trick played on the players. Players can't and should never have to examine cards minutely to see if they do what they promise.
B, in this case is a non-starter, I think. Target is a heavily regulated term, and LoS rules are very clear that you can't draw a line to something that's not a zone.
This leaves C. Turns out that we're not actually targeting in accord with the rules. Yes, I know it has a target written on the card, but the parsimonious ruling seems to be that the card is technically written wrong. I would probably conclude that the cards really mean "choose" instead of target.
So, yeah, they probably needs to be fixed, because they only really work by fiat right now. That's probably mostly ok, but fiat has bad interactions with other rules and cards.