Yea, that's the point and he also says you should plant right away, when beds are done.
To much fertility made me think when i started
gardening. I have always avoided manure and doing very fertile beds. Of course i'm a bit lucky to have humus rich clayish soil and can grow in it without problems, just putting down hay, wait a bit and beds are ready.
What he says makes sense, but i think you've misread a bit. I can not quote from book or anything, so i'm telling you with my own words, not mine, but his understanding.
Nutrient aviability to plants depends on break down of the material inside the bed. Crushed material breaks down faster, so most nutrients are available faster. He says it happens the next year after doing the bed with crushed material. "Of course this totality depends on your climate etc." Anyway, when there is most nutrient aviability he suggest to plant pumpkins, cucumbers, cabbage,
tomatoes, corn, potatoes, ... You should plant peas, strawberries, beans only after four years when there is less nutrients. Plants that are
feed to much are not so aromatic. Spinach can build up nitrate, and that's not good for our health.
Beds out of coarse material, whole logs. There is no high nutrient aviability the first year after making the bed, but then they release nutrients for many years.
What he had available for making the beds was spruce. He also told somewhere you should not cut down spruce logs or anything, more resin is extracted and you can have ph problems.