This is miniscule compared to the amount emitted by burning it. It sort of has to be, or the industry wouldn't exist.
Congratulations, you're now deliberately fishing at the opposite and and nitpicking at the opposite end just to argue, at this point, when you could be looking at the entire pond.
Of course nobody eats 2000kcal of beef, I never said that. I was providing an extremum of all-brassica and all-beef so that you can interpolate somewhere between them, but evidently you're more interested in taking the endpoints and call it nonsense instead of doing the interpolation.
So go ahead and assume drivers eat. Bikers eat more. Again, do the interpolation. You get some data, you do the math, then argue. You will still find that it's within the same order of magnitude. CO2 from food production is a thing, and it's hugely variable depending on diet, that's the point.