Consequently, concerning yourself with the minor advantage one might get when using Spore and Effect Spore on the same set is a waste of time, and missing the point. The point is not that you manged to put two of your opponent's pokemon to Sleep; that's not what the clause is trying to prevent.
Yes it does. Putting more than one pokémon to sleep is our chosen line of when it is abused. It is true that we are trying to prevent abuse of Sleep, but we need a strict guideline for when it is abused.
If you have a rule, you need a punishment for breaking that rule, otherwise it doesn't work. The punishment of breaking a clause is simple; you get disqualified. It doesn't matter that there was only a small chance that you put something to sleep. If you have a revolver with only one round and you shoot at someone's head with it, it doesn't matter that there was only a 1/6 chance. If you happen to shoot that one round, you still murdered him.
However, we've seen that there are several scenarios in which the clause gets broken
unintentially. The thing we're trying to prevent is people getting disqualified when they accidentially broke a clause.
The big problem lies in when someone can be held responsible for breaking the clause or not.
You could say that you couldn't know that your opponent was going to switch in Dugtrio on your Spore-using Scarfed Breloom.
You could say you couldn't know that your opponent wanted to use a contact move on your Breloom.
You could also say that you couldn't know that your opponent wasn't planning on switching in an Insomnia pokémon when you were using Spore.
Saying whose "fault" it was in these kind of situations is completely subjective. To compare our little video game with our court system again, the law simply says "don't kill people", and if you do murder someone, a judge says if it was your fault or not.
..Exactly as how the current Sleep Clause works. If someone breaks Sleep Clause in a big tournament, one of the organizers will say if he gets disqualified.
Even though it's odd for me to say as the OP, maybe the current Sleep Clause is good as it is. It is true that you could get disqualified due to Metronome or a trapped Choicer, but those scenarios are extremely rare and it is impossible to make a clear line for fault, you will always need an opinion.