It is largely meaningless, which is why it's such a stupid gaffe to make. The vast majority of people attending weren't wearing ties, but there is nonetheless an expectation among male dignitaries to do so. Had he rocked up without one it would have been similarly daft. People saying it's disrespectful or whatever are being silly and you sense they'd hate him regardless, but if he didn't once think that getting himself a sober overcoat rather than one with a hood might have been more sensible, then you do have to question his judgement. It's such an unnecessary gaffe.
How is it even a gaffe? The only people who are going on about it are the people triggered by everything he does; in fact if he had turned up in the black coat he wore last year the headlines would have screamed "
Corbyn recycles old coat in new attack on the War Dead" and you wouldn't be able to move on twitter for #FBPE types saying this was why they'd left the party and joined the Liberal Democrats*.
re Brexit, the issue isn't that he thinks what he does, that's up to him entirely, it's that he and his shadow Brexit minister have contradicted themselves within a day of each other. Indeed, if you listen to Starmer his tone was very much one of correcting Corbyn for not seeming to know the policy the party had agreed on. I get that he's your guy and you'll defend him come what may, but these are such silly gaffes to make.
The agreed party policy is that they will vote down any deal that does not meet the six tests; both of them said that. The difference is whether or not Brexit can be stopped - legally it can be (despite May's insistence) but what Corbyn was pointing out is that to do so without doing any of the work necessary to deal with (or even acknowledge tbh) the reasons why seventeen million people voted to Leave is very wrong.
What exactly would the government have to deal with if the country remained in the EU, exactly as it is now? We might need to pay them for the expense incurred in the process, but I’m not sure what fallout would come with things remaining as is.
The EU isn’t perfect, but it’s increasingly evident that it’s a far better system than we can implement ourselves.
There was a list of things in that post, but briefly they would have to deal with the chaos that is the immigration system, they'd have to sort out access to housing and the decline in stable / secure employment, and they'd have to sort out various sectors of the economy (manufacturing especially) that have been in decline for years - all of which were blamed on the EU but were actually HMG's responsibility.
Then they would have to deal with the political fallout, not only in terms of the establishment effectively ignoring a referendum result but also (and especially) with regards to the way money flows into politics in the expectation that politics will do something in return (the scandals highlighted by the Guardian and OpenDemocracy are only the tip of the iceberg) and the role that the media is playing in our politics.
* obviously not in the sense of actually joining them