UK leaving EU weakens the institutions of europe and does scupper any form of EU defence force
Which institutions? The UK largely operates in tandem with European Defence forces rather than as part of them.
tone down US involvement in NATO, then given the swing to the right by the UK and as we also always support the USA
A swing to the right seems more likely in the event of a weak or no Brexit being delivered, as this would allow the far right to recruit more moderate right wing and undecided voters under a banner of delivering a true Brexit. The level of involvement in NATO is a red herring, given that 'supporting' the USA, in this context, would mean a greater contribution, not a lesser one.
we will standby if europe then becomes prey to a resurgent Russia, who won't directly invade but will interfere, either directly as they did in Georgia/Ukraine or via cyber warfare
Georgia/Ukraine aren't part of NATO and therefore don't enjoy the protection of collective defence. As for cyber warfare, ENISA already works with the NSA so there's a well established precedent for co-operating with non-EU nations.
Europe has rivalries that have been held back by trade and the political institutions of the EU,
I think you're minimising the role of the P5 (UNSC).
In 1988, this happened in NI
Non-State Actors, unless the IRA are members of the EU.
Is it a "very different issue" for the civilians caught up in the violence?
Appeal to emotion. If a relative of mine were involved in a derailment, I'd be very upset, regardless of whether it were caused by recklessness on the part of the driver or by the government removing the requirement to inspect tracks. However, the scale of the problem would be different and preventing further incidents would be handled in a different way.
Jesus Christ! how the fuck can any anyone draw a parallel to the Treaty of Versailles and being members of the EEC/EU
As I said:
"fueled by the perception that a group of European nations collectively forced unfair policies upon other European nations"