You say it is disengenious... and yet literally every single time we see people talking about gnomes getting a +2 strength, someone brings up an example like this. Badgers vs elephants. Mice vs ox. wolf vs blue whale. Every. Single. Time.
And, taking it seriously shows that... well, no one is taking these arguments seriously. No one really wants to show biological accuracy in the strength between a badger and an elephant, it is just a smokescreen to make the argument "shouldn't strong things be strong" seem better, and to make the other person have to take a position of arguing against something ludicrous.
So, I want to side-step that. The game isn't trying to show biological differences in strength accurately. It just isn't. It isn't even set up to show that half-orcs are stronger than humans. Because there is no way to show that. Again, the best we can do is some sort of statistical average... but this isn't a game about population distributions. this is a game about individuals. You can't just look at a piece of paper that says "half-orc" and determine if the person who gave you that paper is stronger than the person whose paper says "human". Just like you can't do it if the papers say "male" and "female". You can talk about statistics, probability, you can do all sorts of obsfucation to make it seem like making that decision is reasonable, but at the end of the day they are an individual, and considering I'm much more concerned with +1 to hit and damage (which in the real world is a combination of skill, strength, speed, mass, endurance, and the angle of the cutting edge of the weapon) than whether or not they can lift 30 more pounds than the other person... I don't see what biology has to do with it.
Maybe a gnome +2 strength means that they know how to leverage their mass better, it doesn't really matter, because the game is just using that number to show how effective they are at the job.