How was he being unprofessional? You asked questions, and he answered them.
Actually, your question was somewhat accusatory, along the lines of asking someone "So when did you stop beating your wife?".
You're belief that the batteries will need to be replaced in 5 years is incorrect, and every hybrid vehicle that I'm aware of has at least has an 8 year warranty on them. So even if you HAD to replace them, it would be at no cost to you.
It should also be noted that hybrid battery packs use load balancing logic to extend the life of the batteries. In other words, you are not charging and discharging all the cells at the same time, or one cell all the time. Different cells are used at different times, thus distributing the cycling load and increasing the life. Similar logic is used in many different systems from jump drives to server farms to intesive computations on multi-processing computers.
It would be very difficult to have the entire battery system fail at the same time. Cells may fail or at least attain sucha low capacity that they're effectively useless, but the whole battery pack won't fail altogether.
Now who is being unprofessional? "Fine! I'm taking my ball and going home!"
But I suppose such statements of wisdom don't apply to you, who in another thread swept aside the the volumes of scientific studies on climatology with what amounts to magical pixie dust.
If you don't want information, don't ask.
~X~