FFS - retain some perspective here - this wasn't a HEMS mission so all those arguments are irrelevant. BTW the advice of an ambulance manager who isn't a pilot really isn't pertinent - his job is to keep his medics safe , not make aviation judgements.
Second - they were not deliberately training in those conditions - if you have to get from A to B and you are limited on fuel, constrained by terrain and caught out temporarily by a very localised bit of weather - you do what they did, have a look - if it's not good enough you turn round (if you can) if it is good enough you carry on into the nicer weather.
Remember you can't see the conditions behind the car - ie where the aircraft is going - so you have no clue in your armchair what the crew could and could not see.
Anyone who has flown in that area knows how quickly the weather can go from epic to sh*te and back again within a few hundred metres.
But I would question the judgement of doing in the proximity of a public road like that.
the best aid you can have in those conditions is a line feature - it gives you a visual reference and helps your navigation, The worst thing they could have done is meander 'off-piste'. Anyway, anyone driving fast in those conditions is far more likely to cause an accident than the helicopter's presence.