"If his company has not made a profit it is possible that HMRC would look at his receiving a dividend of £28,000 as not being in line with the company's position, and as such the structuring as a company is being used as a method of avoiding paying income tax."

Not if his balance sheet shows sufficient distributable profits brought forward.

So are you saying that if our nice builder receives a salary of £38,000 and a dividend of £10,000 he cannot choose to allocate £5,000 of his personal allowance against dividend income leaving £5,000 to be covered by dividend allowance, and the balance of £6,500 against his salary - a tax saving of £625 over the HMRC software calculation which would allocate all of the personal allowance against salary????