You can google the phrase "Standard Model" or look it up in any physics book you want, and there will always be a table labeled "Standard Model" that shows all the particles, which relate to the 4 fundamental forces (carriers), charges, spins, masses, etc. I'm sure you're familiar with this chart. The graviton is on that chart and is specifically describing gravity based on each mass value of each particle (hardly "silence" there). I mean literally every particle type has a mass value (even when zero) right? Is that silence? The general laymans meaning of "Standard Model" means everything in physics that is referenced on that chart (including gravity), and that's how I meant it.
However, what YOU apparently mean by "silent on gravity" is referencing the fact that the Standard Model is incomplete for gravity, because General Relativity is not yet accounted for. I should've realized you might be referring to the lack of any unified field theory, but I didn't. If you had said "doesn't fully explain" rather than "is silent on", it would've sounded perfectly fine to me.
However, what YOU apparently mean by "silent on gravity" is referencing the fact that the Standard Model is incomplete for gravity, because General Relativity is not yet accounted for. I should've realized you might be referring to the lack of any unified field theory, but I didn't. If you had said "doesn't fully explain" rather than "is silent on", it would've sounded perfectly fine to me.