On the NG we get a warning light below 800 ft AGL if they're deployed. Can't us them above 300 kts or past the lfight detent. No restriction on usage with flaps deployed.
Sounds like the pilot might be new on the NG. It takes awhile for the new guys to figure out that the speedbrakes are pretty worthless. They're just an airplane vibrator. They don't really appreciably increase you rate of descent for the noise you get.
Best way to descend in an NG is to slow down first with a momentary level off. Optimum drag for descent on a long ILS final from altitude would be Flaps 5 or 10, assuming you wouldn't be droning through ice.