I feel like highlighting just the values before the first comma is arbitrary as well. If we adopt a definition of significant figures based on measurement error, such as
The number of significant figures in a measured quantity is the number of digits that
are known accurately, plus one that is in doubt. (Rounding and Significant Figures, Laboratory Analytical Procedure, National Renewable Energy Laboratory, 10.1.2; https://www.nrel.gov/docs/gen/fy08/42626.pdf)
it is reasonable to claim that significant figures are determined on the basis of the accuracy of measurement, and not based on the appearance of the result.
As an example, suppose we have an instrument, say a 1 meter ruler, that is accurate to the centimeter. Standard laboratory practice is that I should be able to read up to the millimeter. If I use that ruler to measure two lengths of string, and get the results 7.4 cm, and 93.2 cm. The first measurement as two significant digits, and the second has 3. And then to extend that, the sum of those two values, 100.6, has four significant digits. In all of those cases, the number of significant digits is determined by how many digits are between the first non-zero digit and the first uncertain digit.
It gets a little more complicated when you move into multiplication (and a lot more complicated when using logarithmic functions), but the principle still applies that as long as you know the limit of precision of the measuring instrument, you can trace the appropriate significant figures through all of the calculations. Trying to guess the appropriate significant figures from the values, however, is risky business.
Additionally, significant digits are only relevant to measured values. In the initial posting, the columns appear to be counts/integers. Count data isn't subject to imprecision, and so, strictly speaking, significant figures don't apply. The proportion of two integers is also not subject to significant figures; since the integers have infinite precision, the proportion does as well (at least as far as the machine tolerance).
Which brings me back to my question: Is there a theoretical or conceptual justification for the illustrated behavior; preferably something published. If there is, then the behavior may be appropriate. If there isn't, I worry that this behavior will contribute only more confusion to the topic of significant figures.