As gwnn pointed out, the situation which provoked your partner to offer a 'rule' isn't at all analgous to the situation of the OP.
The issues surrounding competing for a partscore are different from issues surrounding slam bidding in uncontested auctions, and rules that assist in one area may have no utility in the other.
To turn to your proposition that opener, on the OP, has an Ace (or more) extra and thus should move: I think there is an undetected assumption underlying your argument....which is that when partner bid 4
♠ he was promising that you would likely make 4
♠ if you held a reasonable minimum.
Now, with his hand, that would be a fair assumption for him to make, altho it is trivial to construct good opening hands on which 4
♠ fails.
But the point is that 4
♠ doesn't promise or even suggest that your side will make 4
♠. Of course there is hope that it will, and expectation that it will often make, but the 4
♠ call is not only a bid of game but also, and importantly, an attempt to preempt the auction.
Thus holding an Ace or even a little more doesn't justify going to the 5-level. Partner may well and often will be bidding in the hope that you will buy the contract for down 1 or 2 when they have a game available.....your possession of extra values simply makes his decision even better. Imagine how you and he would feel if, just when you hold enough that they can't make anything and you make 4
♠, you drive to 5
♠ down 1
I fear you have fallen into the very common trap of analyzing your bidding decisions based on knowledge of the actual hands.
And please don't take offence at this, but the fact that you think that a 'life master several times over' is a 'very good player' says more about your inexperience than it does about the skill level of your partner. Becoming a life master, several times over, is not exactly a challenge in today's ACBL. Now, the player in question may in fact be a very good player, but my experience suggests that there is little correlation between the number of masterpoints and bridge ability, at least in the range of say 500-1500 mps. The club where I play has many players in that range, and not one of them is 'very good' (I don't think any of them read this forum
)
I find it ironic that you seem to accept the advice of this life master yet refuse to accept advice from players who are (I suspect) at least as far advanced compared to him or her as he or she is to you.
'one of the great markers of the advance of human kindness is the howls you will hear from the Men of God' Johann Hari