Eat more protein!

Take these digestive drugs to keep it all down!

Take Glp1 because you are now fat!

Visit our cancer centre to get fitted with a colostomy bag!

This is the US diet in a nutshell.

The RDA issue is addressed in the article I linked

For adults, the US Recommended Dietary Allowance (RDA) for protein is 0.8 g/kg/d.[2] However, a more appropriate statistical analysis of the data used to establish the RDA suggests this number should be higher: 1.0 g/kg/d.[3]

Note that, contrary to popular belief, the RDA doesn’t represent an ideal intake. Instead, it represents the minimum intake needed to prevent malnutrition. Unfortunately, the RDA for protein was determined from nitrogen balance studies, which require that people eat experimental diets for weeks before measurements are taken. This provides ample time for the body to adapt to low protein intakes by down-regulating processes that are not necessary for survival but are necessary for optimal health, such as protein turnover and immune function.[4]

An alternative method for determining protein requirements, called the Indicator Amino Acid Oxidation (IAAO) technique, overcomes many of the shortcomings of nitrogen balance studies.[5] Notably, it allows for the assessment of protein requirements within 24 hours, thereby not leaving the body enough time to adapt. Studies using the IAAO method have suggested that about 1.2 g/kg/d is a more appropriate RDA for healthy young men,[6] older men,[7] and older women.[8][9]

That's how much you need to eat when you're trying to actively gain muscle, not just maintain your current amount.

And quite frankly, either put on that much muscle or kindly accept that they may have a point.