No, there is no substitution of protein for the lack of carbs.
I don't seem to require any bolus insulin for protein providing that I am eating my usual amount of carbohydrates. As soon as I cut out the carbs (<30g or so per day) - I require a bolus for any protein eaten, at about half of that if it were a carbohydrate.
I think the reasoning for the above is some phenomenon called gluconeogenesis?
Long story short, considering I need to inject insulin regardless whether on a moderate carb diet or low carb diet - I'd chose the moderate diet to give me more choice. I'd consider LCHF at a level such as <20g per day if it meant no bolus injections, but unfortunately it doesn't so I'll stick to my tatties and pasta
I think my input to this thread is more or less void as I'm not diet and exercise controlled T2 so my points aren't entirely applicable.