Competing for the partscore... in notrump?

[rod]

An interesting bidding problem was posed on the Bridge Winners site where you have:

♠ J5
♥ 7
♦ KQ964
♣ QJ1082

and your LHO has opened 1♠, partner overcalled 2♥, pass pass to LHO who bid 2♠, back to you.

Now what does a 2NT call mean? Natural or minors?

Bridge World Standard says:

Forcing vs. nonforcing: When a call could logically be interpreted as either forcing or nonforcing, and there is no explicit agreement: In a competitive situation, treat as nonforcing

Now I've seen players bidding 2NT naturally in situations like this, even successfully. However it seems more useful for 2NT to ask partner to bid one of the unbid suits. So you really need a partnership agreement that, as generally as possible, covers situations like this. Here is what I suggest:

When competing for the partscore and both partners know that values for game are not present, a call of 2NT is not natural. It's similar to a takeout double but with more length in the unbid suits.

What do you think?