No, you want them to fill out their profile so you can definitively know they are spammers vs. new sign ups that just never come back for “unknown reasons”, this will haunt the minds of every metric obsessed manager and they will never let you delete these “users”.
Strongly opposed, also, this was covered at extreme length in existing topics..
I support Akismet profile checks and auto delete of users who never come back and never read anything.