I see your points but...
1. say even if you do store more off chunk.. then whats stopping the person from killing the next batch also? and to restock your supply.. oh yeah breeding...45 min waste. and the amount of land required to do compound breeding like your method suggests would be quite a lot. In case others don't know, sheep do not spawn babies if there are more than 2 sheep on the same chunk. To get every sheep to breed would require their own chunk just to breed on. at least 5 or 6 extra chunks just to do your method.
2.spawn eggs? wayyy to expensive to just be killed in 1 sec by someone.
3. Yeah you can use spawners( for them to spawn more you have to transport the sheep out of the area of the spawner) but those do cost a fair bit of money, also dyed sheep don't exactly spawn like that... some dye types so cost a fair bit to make, try cyan for example(
smelted cactus +lapiz). If your purpose is a murder farm then by all means go ahead use a spawner but if your purpose is to be practical...
4. how exactly do you propose blocking a person? there is 0 way of finding out who did it unless your actually there watching your sheep 24/7... I don't know about you but I get bored of counting sheep after the first hour. Trying to figure out who did it would just be a waste of time for staff members.
Larry are you being paid off by the crafty's?
It may not seem like it, but I do actually know proper grammar.