Jambo Zenj!
Very strange feature, and absolutely crazy and dangerous!
Are you SURE it's a -200 feature, and not simply a malfunction or mishandling on that particular airplane?
I would be VERY surprised if Boeing had designed such a feature on earlier 737s...
I flew the advanced -200, but I can't recall such a dangerous feature...
On the contrary, first of all you can always pull reverse thrust on a classic, even before touchdown, below 10 ft RA (although prohibited, this is a safety feature in case the air ground sensor is not triggered upon touchdown... and coud save your day if you are floating badly on a short runway...).
Second, the system is designed in a way that even if you forget to arm the speedbrakes, they will extend automatically when you pull reverse thrust, exactly as it happens during an aborted takeoff.
Some operators even adopt in their SOP this sequence during RTO, to save some tenth of a second: close the throttle, pull reverse, THEN make sure the speed brakes have extended.
IF it works, you definitely gain a few tenth of a second, but I disagree on this procedure... search for some interesting thread on this subject on this forum, it has been discussed at lenght before.
Happy flying in my beloved Africa!
LEM