Food for thought
Kuwait340,
I don't use this method all the time nor exactly the way he did it but my reason for doing so is simple: I want you down first, then slow later.
On one of our runway ops, it seems that we always have a tailwind to 2,000 feet and then a slight headwind. You can imagine the shrinking effect this can have on spacing. So, often enough, I'll instruct a crew to descend with a good rate and when level to slow down.
I'd much rather have you in the same wind and slowing down than at the same IAS as the previous traffic but still with a 40 knot tailwind.
In my opinion, what your friend wanted was simple enough: He wanted the altitude first, to resolve a coming conflict, and the second part of his plan was to have you reduce to follow someone. But he needed you down first. If you end up reducing your rate of descent to slow down, you might ruin his plan...
Food for thought?
Felix