He's kind of right though, although not very polite about it ;p, you missed the lights. With that amount of 1000w I bet his lower bud is heavier than most 600 growers mid bud and his mid bud as dense as their top. I would sooner agree with his number than try to call him a liar simply by looking at a pic that does not translate density very well and it also seemed you gave a number assuming 600w lights. 10 days worth of trimming would also possibly back that up as he trimming a lot of the more time consuming lower stuff that may not even develop under 600w if the grower didn't cut it away anyway.
What ever the case why automatically assume somebody is a liar, not just you, the others too. All I can read into that type of attitude is projection of your own limitations.
If he is a liar, so be it. He got the attention either way ;p.