at the same time, if I ever write something like this it will all have been worth it.
I think you should read the whole thing where he takes their claims apart piece-by-piece but here's an excerpt from the end:
Let me be clear about this: there are only two ways for you to get anything out of me. You will either need to (1) convince me that I have infringed, or (2) obtain a final judgment to that effect from a court of competent jurisdiction. It may be that my inability to see the pragmatic value of settling frivolous claims is a deep character flaw, and I am sure a few of the insurance carriers for whom I have done work have seen it that way; but it is how I have done business for the last quarter-century and you are not going to change my mind. If you sue me, the case will go to judgment, and I will hold the court's attention upon the merits of your claims—or, to speak more precisely, the absence of merit from your claims—from start to finish. Not only am I unintimidated by litigation; I sometimes rather miss it.
Hot! Hot! Hot!
I find it striking how people who are writing letters of complaint usually can't do it this well. Lots of people try to make the other party feel bad, make moral judgements and exaggerate their issue with crazy comparisions and/or obvious advertising fluff treated literally. You'll note how this gentleman doesn't say "When you accuse me of violating your patent, it's like a human rights violation in Darfur" or "Your company motto is 'Excellence in Cables,' but you have failed to be excellent in the following fifty ways:". He keeps it focused on the issue at hand and strictly practical about the matter.
And I suspect he will get exactly the result he wants with no additional fuss.
who has found the "only madmen write letters in excess of three pages" rule to be accurate, usually, but is delighted to consider this an exception to the rule.