Yes, I agree, but the dictionary definition (rather than the tax man's definition) of residence is somewhere that you live. If you live there for a short period every year and if mail sent there will reach you, I would say that it counts as a residence. Certainly, whenever you will be driving the car you will be living in the UK and that makes you resident (in the dictionary sense).
If you are uncomfortable, you should ask the insurer for their definition of a UK resident. Some insurers require that the policy holder has at some point lived in the UK for 6 months or more. This is not the same as the tax man's definition.
My opinion is that you should not tell them that your situation is in any significant way different to most other drivers and you should try not to have any accidents.
You should get a discount because the car wont be in use for most of the year but that wont happen.