Indeed - if someone ingested any quantity of eliquid at almost any strength it could be very nasty (or worse).
However, it is important to realise that when you vape only a proportion (I suspect small - I recall seeing something about analogs which showed that with them the proportion is VERY small) of the nicotine in the liquid is actually taken in by you. Also, vaping is a gradual process - we all know that you can make yourself feel "off" by vaping excessively. If you vaped 54mg juice this would just happen quicker, it still isn't so strong that you could kill yourself accidently by just vaping I'm sure. The UK has a limit of 75mg on nicotine liquid before it becomes subject to heavy regulation.