https://arxiv.org/abs/2404.10002
Abstract (emphasis mine):
The concept of a 'Ballmer Peak' was first proposed in 2007, postulating that there exists a very specific blood alcohol content which confers superhuman programming ability. More generally, there is a commonly held belief among software engineers that coding is easier and more productive after a few drinks. Using the industry standard for assessment of coding ability, we conducted a search for such a peak and more generally investigated the effect of different amounts of alcohol on performance. We conclusively refute the existence of a specific peak with large magnitude, but with p < 0.001 find that there was a significant positive effect to a low amount of alcohol - slightly less than two drinks - on programming ability.
To be fair, if they really, honestly, stick to one or two drinks, they should be under the legal limit in most places in the US. This depends on their weight and the strength of the drinks, too, but anyone over 120 pounds is normally still under the limit after 2 average strength beers.
The problem is that it's easy and tempting to overdo it, but as long as they have self discipline to not ever drink too much, it can be fine.
Legal doesn't mean safe; it just means the lawmakers are too corrupt, stupid, cowardly, or weak to tighten the limit.