I think they're just being cautious. Ideas need to become policy. Policy needs to then be tested before the public hears the specifics. It takes time. The surest way to end their 'movement' would be to say too much, too soon and with too little thought going in to the specifics.
It's worth baring in mind who the new Labour leadership are - a ragtag bunch of disparate but capable MPs who you wouldn't, under normal circumstances, see in a room together. That doesn't mean it won't work - there's some very capable people in the shadow cabinet - but it will take time for them to build a cohesive plan. Until then, expecting specifics is pointless - only an idiot would try and give them to you.
It's worth baring in mind who the new Labour leadership are - a ragtag bunch of disparate but capable MPs who you wouldn't, under normal circumstances, see in a room together. That doesn't mean it won't work - there's some very capable people in the shadow cabinet - but it will take time for them to build a cohesive plan. Until then, expecting specifics is pointless - only an idiot would try and give them to you.