The way I see it, LE slats are lift enhancers. If Reverse is selected, I think extra lift might be unnecessary, even counter productive. Stowing all lift enhancers seems a reasonable thing to do when your goal is to slow down. Leaving drag devices deployed likewise seems correct. (Flaps and spoilers).
See it any way you like, but the design purpose of the inboard and mid-span LE devices retracting with reverse selected is to prevent fatigue on said devices. It was never designed as a method lift dumping, at which it would actually be of very limited use (consider the angle of attack of the wing after touchdown).
Imagine the scenario -
On rotation you get the stick shaker and two amber R's (inidcating you have two unlocked reversers).
The crew dont know the inboard and midspan LE devices have retracted ..
It would be extreemly tempting to assume the amber R symbols above the EPR are the problem and call for an engine shutdown ...
A point that cannot be stressed enough. It's all very easy to look at this incident with hindsight and suggest you or I would have acted differently (ie gear up or not) - but in a time limited situation I think they did a fantastic job of prioritizing the flying of the aircraft. Kudos to them.