[pescetom]

Here the customer makes a slight overbid, but there are no prizes for letting people bid 2♣ sequences without interference.
Robot (often so glib about The Law) gives misinformation about its raise to game and then passes over small slam, either knowing the customer by now or thinking this is an elite field.

[smerriman]

The definition is just another case of GIB being unable to use the word "or" in its descriptions; its rule for a preemptive raise to 4♠ promises 4+ spades due to the law; but there's a much more general rule about when it's allowed to bid game in a major in any bidding situation, and the only thing those rules have in common is a spade fit, thus the overlap being 2+ spades.

I don't think that more general rule is even theoretically possible to match in this sequence, but due to the database format, it can't figure that out.

Preemptive raises to 5♠ or higher don't exist in the database (which I guess is the real issue here), so 4♠ is its only option for the first bid.

Having preempted to 4♠, GIB is strictly forbidden from considering raising its own preempt later. A rule I'd wish some human partners adhered to in general..