you're right and I'm wrong, sorry.
In fact, the setuid bit on directorties is ignored on unix and linux. And it is not the case on freebsd where you can mount filesystems with the suiddir option that will allow that behavior.
If you really want to be able to do that without having to become root, you may make a little program that will change the ownership of files, with owner apache, the setuid bit set, group user1, read and execute flags on group and no read nor execute for other users.
I'm Sorry I couldn't help more.