I've changed my mind about questioning BIttrolff's convictions. District Attorney Ray Tierney seems too smart and savvy to pass up a chance to further a political career by "righting a 20-year wrong" if that were a possibility.
If Tierney has aspirations beyond his current position, he has to know how well freeing someone wrongly imprisoned would play in any campaign. It would make him appear to be more interested in justice than the win/loss tally. This is the highest profile case of his career, that's why he's trying it himself - IMO. So, would it not be "icing on the cake" to right a great injustice of 20 years ---
if that were a possibility?
I've been outspoken in my desire for DA Tierney to be very specific as in: "We've closely examined all the evidence in the Bittrolff convictions and there is nothing NOTHING to suggest RH is involved, not a dab of DNA nor a single hair belonging to him or any known associate." That's what I'd like to see to be positive of the convictions. However, since Tierney hasn't worked to overturn an injustice, I suspect they're good convictions.
Changing the subject to the rest of your post:
According to the Wikipedia article on Dennis Rader, he suggested BTK (among "many others") as a name for himself in 1978 in a letter to television station
KAKE, in Wichita, claiming responsibility for the murders of the Oteros, Bright, Vian Relford, and Fox.
IF RH were following serial killers, isn't it likely he would be familiar with the "BTK" name by 2000 when he was writing the HK document? While it could easily be for HouseKeeping, as suggested, I think Hunt Kill or another shortened form of his MO is also possible. Unfortunately, we'll never know unless he starts talking.