The way the bill is structured, and it's structured this way intentionally, is to leave the option to the parent to either apply for a grant of citizenship or to apply for a permanent resident status for the child. The reason is that in some cases the parent may want to maintain the potential for that child to keep his or her foreign citizenship. So that two-track option is intended. It's up to the parent or the adult adoptee to make that choice to apply through the citizenship or the immigration process.
On June 21st, 2006. See this statement in context.