I don’t think the post is being dismissed because it’s in the Observer. I think it’s being dismissed because it’s a complete non-story.
In that sense it’s part of a tiring trend when remainers are sifting through every single issue they can think of to prove that their apocalyptic warnings have some (any) substance.
As the ONS report - which the Observer ‘story’ was ‘reporting’ on, in the loosest sense of the word- makes clear these reductions are temporary, were largely due to Covid and stockpiling the month before and that a similar process happened with imports from the EU which actually fell more sharply than export. Most significantly, the ONS report showed how things were returning to a normal state of affairs as the month went on.
The headline about the transition, if there is one, is how smoothly it actually went given Covid and the end of a trading relationship that had been in place for 50 years. As you rightly note given the clowns involved imagine the possibilities if we had anyone even half competent running the show...
In summary. I think most of flack remain is copping is due to the fundamental dishonesty of its arguments. Plenty of us would engage with any substance that the remain side might want to advance, but planet remain seems to have abandoned serious analysis, as anyone with serious politics on their side has accepted matters and moved on leaving only the true believer types.