The delay allows the person challenged time to flee to a safe location if they so wish, or at least to prepare to face the coming onslaught. Removing this time period would make challenges the equivalent of an everyday jump.
I fail to see what the problem is with you challenging from a runed guild location for example, as this would give both parties time to prepare and I'm sure that you would want an honourable challenge.
Finally, I note that after you challenged someone, you then went and killed somebody else. Seeing as the rules suggest that people should not interfere in challenges, does that not strike you as abusing the rules?
Written by my hand on the 7th of Cloudburst, in the year 1001.