British child moving to Oz

I am an Australian citizen living in the UK with my British child. My son is eligible to obtain Australian citizenship by descent, however I have not yet made this application. We are intending to move to Australia soon and I have the follow question.

Is there any advantage to NOT applying for Australian citizenship by descent for my son given he will soon become a resident of Australia, and therefore will at some point be able to naturalise rather than inherit his citizenship from me? (And therefore have the advantage to confer his citizenship to his overseas born children one day should that situation arise).

Or have I missed the point, and my son is AUTOMATICALLY Australian (by descent) already whether I formally register him as such or not, and as such naturalisation will never be a valid route anyway?

Thanks in advance for your answers clarifying this for me before I proceed.

I am a citizen by descent (my father registered me in 2001, I remember attending the interview in Queensland with him so it was not automatic but it was a quick process). At some point before my children turn 18 I will have to move to Australia with them for a certain amount of time in order to naturalise them or else we will lose the option to pass on citizenship. If I had my druthers, I would rather have been naturalised rather than have been registered by descent, although it wasn't an option for me.