It's an equivalence of sorts but it's also 'whataboutery'. Shifting the argument to another topic. Consuming food on a train isn't illegal. It doesn't and shouldn't require meeting some 'consideration' threshold. People eat because they have to, not because they are inconsiderate.
Playing videos or listening to music without headphones can be illegal on a train. So it is in fact a false equivalence.
Railway Byelaw 7:
7. Music, sound, advertising and carrying on a trade
(1) Except with written permission from an Operator no person on the railway shall, to the annoyance of any person:
(i) sing; or
(ii) use any instrument, article or equipment for the production or reproduction of sound.
<snip>
No need to move in that instance. Request they stop and/or report. The law is on your side.