Most likely because the emergency services didn't know what they were dealing with. Somebody calls them on 999, describes a blue body, unexpected death . . . . . . recent memories of the Novichok nerve agent used in Salisbury will be in their minds.
Of course, that has to be conjecture on my part, but it seems to be a very plausible explanation to me.
It's likely that more and more reports of SN deaths will appear in the press, given the explosion of interest and awareness in the method. So far the reports seem to be local news, reported in local newspapers, but I predict it won't be too long until a national media outlet, be it press or television, picks up on the matter. Then we'll have the usual sort of response: a national newspaper will "campaign against killer chemical," a TV expose in something like
Panorama* will be aired, and there will be pressure for "something must be done."
I've pointed out in several posts over the months just how easy it would be for a UK government to bring SN into the legal category which needs a licence to acquire and keep - there is a "Henry VIII" clause in the Poisons Act which can facilitate this. There may be some food industry reluctance to see this happen, as they would not like to see a chemical which they use widely being highlighted as a deadly poison in this way. Possibly a voluntary code to restrict supply may be suggested, and the indications (to me at least) are that this is already happening.
Timewise, the authorities have the drop on us. They will have been able to collate reports of SN deaths long before they are made public. In this case (post #44) there has been a 3 month lag between the event and the press report.
No doubt there will be nitrite/nitrate confusion in reporting, though the reports have so far been pretty accurate in that respect.
*My reference to
Panorama won't mean anything to non-UK Forum members. It's a BBC current affairs/news programme which has done some good investigatory work over the years.