The author claims the cost for the UK of the navy is 0.6% of GDP, and the cost of not being able to access the Suez canal is 0.06% - ten times lower. My problem

The author claims the cost for the UK of the navy is 0.6% of GDP, and the cost of not being able to access the Suez canal is 0.06% - ten times lower. My problem with that argument is that the Suez canal is not on the only shipping lane that the UK is using, and thus interested in 'protecting'. Maybe the proportional cost for 'protecting' the Suez canal as part of the whole navy budget is much lower than 10%, in which case the economic calculation may come out ahead.