I’m sure you have reasons for saying this, but I am not a mind reader! If you don’t say how or why you have arrived at a conclusion, it doesn’t help anyone understand your perspective.

If I had to guess, I would say you might be saying this because the residents of the Isles of Scilly would still be hugely outnumbered by the “mainlanders” in this district. It really depends on what you see as the purpose of these districts, and how flexible their internal workings are.

Either as an entity to interface with the state government, or as an entity to provide certain critical municipal functions, the Isles of Scilly are just too small to be effective. As mentioned:

“On their own, the Isles of Scilly make up around 0.1% of the population of Kernow, so keeping them as a district by themselves would both involve the Kernow state government having to deal with a tiny authority which would be quite inefficient, as well as having the local authority itself being comparatively large with respect to the population it serves.”

That being said however, there is nothing to stop a district being further divided and having special status or functions for certain areas. As discussed here and proposed here, semi-autonomous zones and federalism within federalism are a good way to manage some of the more unusual communities.

Ultimately each governmental function needs to be devolved to the appropriate level. There is no reason the Isles of Scilly couldn’t have more devolved to them than other tiny district subdivisions might, as long as these devolved functions are not ones that will suffer from having such a small population.