It partly had to do with timing. The technology to create the Eugenics Program was created and implemented at breakneck pace. When it was ready, Kerensky wanted it put into action BEFORE Klondike started.
I think he thought it would serve as extra motivation to the troops. They didn't need to fear death themselves, what they did need to fear was failure. Future generations counted on them to excel and succeed.
Op. Klondike page 33.
“Our time is come! We no longer need to fear our own mortality, for we are the immortal warriors for all time. Our children will forever sing the praises of this, our triumphant and just return to the worlds that our Great Father chose for us. We will strike and give no mercy, no quarter, to those that oppose us. But we must also embrace these poor souls, so that they can come to know the peace that we bring.â€
—Khan Jason Karrige, address to Clan Widowmaker, 15 March 2821
Although not all fought well or survived long during Klondike, most had endured the 15 years of testing, training and preparation. They were the familiar faces, they were the "family" of Clan Warriors, the best of the best, the cream of the crop, and so honored appropriately with a Bloodname. They carry the genes of success, even if the individual tales and stories of those warriors varied in terms of how successful they were.
All that said, I think Kerensky could have taken the opportunity to expand the Bloodnames after Klondike ended, awarding those auxiliaries who stepped up and performed well. 803 Bloodnames means a gene pool the size of a puddle. It could have been bigger.
Personally, I've always believed that some of those auxiliaries ended up being among the 600 legacies added to bring genetic diversity to the Eugenics Program. In the early days of the Clans, a warrior legacy was paired with one of those 600 legacies, rather than both gene parents being warriors. Those 600 civilian legacies weren't considered Bloodnames, but they were added to the gene pool.