There'll be a massive difference between for example South American cereal fed beef and something off a british grass based system? Got to know what the numbers actually work back to.....OK, using your figures that works out as 3.9kg of beef a year producing 604kg of CO2e.
Now, according to the NBA, the UK produced 922,000 tonnes of beef in 2018. Using the figures above that would equate to 142,791,794,871kg of CO2e. That's 142.79Mt of CO2e. This is where it starts to look like that emissions calculator is seriously ropey. According to the Department for Business, Energy & Industrial Strategy the UK, in the same year, produced 364.1Mt of CO2e.
Does anyone honestly believe that 39.2% of the UK's GHGe in 2018 was solely down to the consumption of beef? Nah, me neither. Especially when the same BEIS report states that agriculture (all of it) was responsible for just 5.6mt CO2e out of a total emissions of 364.1mt CO2e.
EDIT: as I posted others point out the same......