The patient comes from a country that almost entirely uses "Imperial", or more accurately, "US Customary". Let's call this country "The United States of America".
His mental condition is affected and colored by the constant viewing of these measures through his everyday life.
This causes the patient to fantasize about situations where metric could exist but mostly doesn't.
This could lead the patient to falsely claim that he is from, for example, New Zealand or Australia. A place which is largely metric. In his mind it will be totally metric.
For countries in a state of "bi-measurement", such as the UK, his fantasization will become most strongest, where he will imagine the use of metric in the most obscure of places.
Despite being shown otherwise he will convince himself and try to persuade others that his fantasy is true.
This leads to "awfulization" of events, for example portraying produce sold in imperial to be less tasty than that which might be priced in metric.
Another example would be a "kilometer", ie it will make a road become imagined as sunny and warm compared to a "mile" of road being stormy and dark.
It also leads to a delusion characterized by converting imperial or USC figures to metric and convincing himself that in fact the reverse conversion is the base conversion.
The individual cannot visit the United Kingdom for reasons of fantasy-realization.
He also sees the UK as a reason for the US becoming metric on the back of the fantasy that the UK --IS-- metric. He convinces himself that if an international audience reads his fantasy those who use imperial/USC, especially in the US, will become marginalized and decide to change. Without an understanding that very few people will read his views and virtually noone will believe his fantasies he will continue to slide farther into fantasy and delusion. This includes any other parallel fantasy - including economics.
Although this might be seen as comedy to many, those who laugh at him should realise that a comedy intent is not intended and that he should be treated at least as someone with problems. With issues.
Would you laugh at an old-age individual for not remembering a very recent event?
Think about this when reading his points of view. It's very important.