It's somewhat unusual, but, yes. Three tasks comprise the VCI of the WISC-IV (only two in the new WISC-V). Two of them can be answered quite successfully with one- or two-word responses. The third (knowledge of social conventions--the Comprehension subtest) requires a little more language, but not as much as you would need to do well in social communication. Impairments in social communication and abstract language are most likely to show up on speech and language measures, like the CELF-5 or the CELF-5 Pragmatics. High auditory working memory translates to high Digit Span scores on the WISC-IV WMI.
The WISC looks at verbal reasoning, rather than communication, which is what an expressive/receptive language impairment describes. There is overlap, of course, but it's not 100%. Hence, cases like this. (I've also seen occasional cases where the CELF scores were average, but the WISC VCI was much lower.)
