I mean technically it's only true that scoring slowly is sub-optimal play if your expected total is less than if you got out, but this value is obviously dependent on the number of balls left in the innings. Teams must employ a nerd who tries to work this stuff out, or maybe just give Chahal an Excel spreadsheet.
I am going to slightly extend this to explain the argument I was making at the start of this discussion about RCB's strategy. The assumption is that the end goal of a team is to maximize the number of matches they win. This is some math that might appear non-sense to some folks and I apologize for that and the length of this.
It's almost straightforward to assume that trying for more than par (conditional to the pitch) will reduce the expected value because just by definition the pitch is not conducive to that rate of scoring , the second thing it will do is increase the score variance. For most teams a par strategy is fine, just by definition a par score (conditional to the pitch) probably gives them around a 50% chance of winning. The other component to this is that for most teams the par score
[P1] (conditional to the pitch) is about the same as par score
[P2] (conditional to the pitch + their bowling attack).
Now we bring in the case of RCB where the bowling is terrible enough that P2 >> P1. It's hard to assign a numerical value to this but from whatever I have seen they need about 25 runs extra to compete at the same level. So, P2 ~ P1 + 25.
Now the Win% of a team is probably a sigmoidal curve centered at P2, given the shape of these curves I assume being P2 - 25 leads to a win probability of ~5%. Which I think is RCBs win %ge if they aim for and get to P1.
Now if they aim for P1, then the expected score is around P1 itself. If they aim for P2 instead the expected score is less than P1. However the key component here is that aiming for P2 is a higher variance endeavor. So across a group of 4 matches they probably end up at ~ P1 - 30 in 3 matches and P1 + 30 in 1 match. Ending up at P1 - 30 does not significantly change their winning probability (probably goes from <5% to <1%) because it was abysmal to begin with, however the one match where they end up outscoring the par, their win% shoots up from ~5% to ~60%.
P (Winning at least one match from 4 if they aim for P1.) ~ is around 19%
P (Winning at least one match from 4 if they aim for P2.) ~ is around 60%
Obviously this involves a lot of garbage numerical assumptions which can be immediately challenged and thrown out, but I am using them to mostly explain where I am at intuitively. Their team is garbage enough that they should basically be going for broke each time they play and think of maximizing wins in a group of matches instead of maximizing their expected score per match. In a sense it's no different to a weaker team dishing up a lottery pitch to the stronger team.
[All of this is actually separate from the issue wherein I think Kohli went slower than needed at phases even ignoring the need to go for broke.]