So.. more than one perspective on this:
1. The publisher explicitly describes the series as test prep for cognitive assessments including the Wechslers, Stanford-Binets and all of the major GT assessments most commonly used by school districts and private schools. So from that point of view, yes, it is definitively test prepping, and competitive-entry private schools have a right to exclude them--but I think enforcement that de-activates an application should fairly be invoked only if it is clearly well-understood by the application population well in advance that this is not allowed. I am assuming that in LLL's community this is clearly understood.
but,
2. If the sample pages for the beginner 1/2 books are representative of the activities in them, then most of them are within the realm of a high-quality preschool or kindergarten curriculum, with the exception of the figural series--which the publisher even goes so far as to point out are similar to the CogAT, etc. I wouldn't even worry about the attribute blocks. The blocks I saw on the publisher's site were pretty typical of preschool educational materials (shapes and colors). And the connecting blocks are just the classic unifix cubes. I expect I still have a bunch of similar blocks lying around my house that I bought off Amazon or at the dollar store. (Although since my children are all well beyond that developmental stage, I should probably give them to someone who will use them!) Now if you had Wechsler blocks like the ones used during testing, or something similar, that would be a significant problem. (...and I have those too...but my kids aren't playing with them!)
FWIW, the sample pages from the next levels up (grade school) skate substantially closer to violating intellectual property laws for major cognitive tests. Those are clearly test prepping.
IOW, technically, yes, it is test prepping, but no, I don't think I would have DQ'd your child's scores either. And to the more important question about educational fit, no, I would not worry that he will be misplaced if he attends the local GT school. It is unlikely the question of fit will hinge on a few points one way or the other on the WPPSI.
And remember, (and this goes for any school and many other parenting decisions) even if it does turn out to be a poor fit for him, you can always change, even in the middle of the year. Don't ever feel like you are locked into a specific pathway for yourself or your children, especially at the expense of the health (physical, mental, etc.) of your child, yourself and your family.
