I was playing a live ACBL speedball game the other night and this came up:

1c p 1d p 2c p 4h (no alert, when clicked came up with "not discussed").  I asked the 4h-bidder privately if it was a splinter or natural and just got the "not discussed" response.

I called the director and got the ruling that our opponent was correct in disclosing nothing.

Does this mean that I can just sit down with an expert partner, discuss just the basic card, and leave all other situations up to "expert standard" and reply to a potential neophyte player "undiscussed"? 

I have always alerted and explained bids to my opponents even if undiscussed with partner but it seem this is 100% wrong and putting myself at a disadvantage.

I look forward to hearing the feedback on this!