NFL Ref Jerry Markbreit disagrees with you:
Another question regarding the two-minute, fourth-down fumble rule, what about a dropped lateral? Is that considered a fumble and not advanceable or does the ball have to be fumbled forward for the rule to take effect? --Matt Cox, Bloomington, Ill.
It is a forward pass if the ball initially moves forward to a point nearer the opponents' goal line after leaving the passer's hand or, the ball first strikes the ground, a player, an official or anything else at a point that is nearer the opponents' goal line than the point at which the ball leaves the passer's hand. A backward pass is any pass that is not a forward pass. The phrase, "lateral pass," does not exist in the NFL rule book. Lateral passes are backward passes.
A fumble is any act other than a pass or legal kick which results in loss of player possession. The term "fumble" always implies possession. If an offensive player fumbles and then recovers his own fumble, he has regained possession.
So to answer your question, any backward pass can be advanced and recovered by anyone, unlike a fumble occurring during the two-minute/fourth-down situation.
A backward pass is not a fumble. (emphasis added)
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