I agree with this sentence: (maybe you have interpreted it differently)
By the time you have bought tagged-cells, balance leads, protection boards, suitably large heatshrink, etc. it may not be worth your while, in cost and time?
It is not negative, but is it worth your time and money (that is what it says)... In my case I prefer to work on the trains, build stuff that is intriguing, and a battery pack is just a commodity to me.
I do not see where the term VERY NEGATIVE comes from that sentence, if I was a novice I would interpret it as data, from a person clearly more experienced with me. Since he also kindly provided THREE links to information on building the battery pack, I think you are way too harsh with VERY NEGATIVE.
Very negative to me would be "you are a fool to try"