I disagree on three fronts.
First, it is grammatically proper for "before" to be treated as subjunctive. That is, it appears in the same context as when someone says "Repent before it's too late". "Before" only indicates that it's possible that the future event will happen, not that it must.
Second, there's no requirement that the Attack happens right after the PtA. The text doesn't say "immediately before". If I use PtA, I could take an Attack action next round and fulfill the "before" clause. Or two rounds from now. Or tomorrow.
Third, ruling that an Attack action must be taken screws over players when they use PtA but are later unable to attack. Consider if a player uses PtA and the target Falls Back, resulting in the target no longer being attack-able (maybe they fall of a cliff, maybe they activate a floor plate that closes a portcullis between the two combatants, etc). The player is now left with no opponent to attack. Do you force the player to take the Attack action and effectively waste their turn, or do you let them take a different action to respond to the new battlefield conditions? There are a multitude of situations where changing conditions mean an Attack is not possible after PtA is used. Rulings that require you to predict the future are problematic to enforce.