I think the truth is worse. I think the NHS doesn’t want it to be shown that children like this can be treated and have some level of recovery because then there would be a demand for the NHS to provide those services.
Even if this child were taken care of in Rome at no UK G’vt expense a precedent would be set and they would be pressured in similar cases in the future. The underlying assumption and governing principle is that the child will not produce enough to be worth the $ cost to NHS. That is a very slippery slope.
More like a cliff.