Yes, allowing 5th & 6th place wrestlers to advance (if a vacancy exists in the district) is a very good practice. After all, this is a DISTRICT Championship. And, don't we want the best wrestlers to represent our District?
If a 5th or 6th Place wrestler were to "bump-out" a wrestler who did "qualify" the previous week, then I would say they (5th or 6th) worked harder and became the better wrestler. That is the wrestler I want representing my District.
Furthermore, there are (up to) 8 wrestlers in the bracket at Districts. If anyone out there is worried about the 5th or 6th place wrestler from Subs, instead of the 1st & 2nd place wrestlers (which equals 4 wrestlers), you might re-think your logic.
Each District is given the "latitude" to allow or not allow this practice of advancing 5th & 6th place. In District 1, it appears that the brackets were seeded with the top wrestlers from each Sub, and the rest (byes, 5th, 6th) were "drawn-in".
Finally, the rules say "There will be four (4) qualifiers from each District to State." I interpret this to mean only 4 wrestlers advance to state. So, don't fret - your 4th place wrestler can't be bumped from State by anyone but a "true qualifier".