Rail Staff on here will be 'defensive' on saying too much, as it is against the social media policy, and could also be sensitive information, Those at the sharp end, when an incident starts, will indeed have very little information, that may take some time to actually work out 'what and where' by which time those who are currently waiting will have moved on anyway, station staff will have their hands full directing passengers, revising train services to have time even to call Control to find out the ins and outs of what happened, Control will also be in the thick of it, sorting things out, more accurate info will be available later, and will be put out, but those caught up at the start, and maybe sometime into the incident, may well be told operating incident, sometimes as a Signaller and involoved with late running / revisions, I still only know it as an operating incident, we find out eventually, but the main drive is getting the service back to some sort of normality, we don't need to know what happened, we need to know what the incident, whatever it maybe affects us and the service, better to have a simple generic term, than spout something that turns out to be a load of rubbish !
Having said all that, when I am not at work, and there is trouble afoot, the AGA twitter account does seem to put out info, as soon as they have concrete knowledge of the issue.