He could if he pays it to himself at the right time, towards the end of the tax year, when he knows what his other income for the year is.
Well, if he's sure, he's sure. But if not, then fair enough, because the effect can be worse than he might expect:
Captain Bird's Eye has bank interest coming in to cover at least his personal allowance and 10% band, and then some. Now he pays himself a dividend from his limited company through which he runs his children's parties and TV commercials, being careful that the grossed-up divi takes him just to the higher rate threshold and not a pound over. Unfortunately, he'd forgotten about £1000 profit from sales of records of sea shanties.
At worst, he reckons he'll just have to pay £400 tax on the record sales, but in fact he'll be paying £220 on them plus £225 on the £1000 of GU divi which now unhelpfully sticks out above the threshold, won't he? That'll put a right shiver up his proverbial timbers.
To say that something is tax free *subject to certain conditions* is equivalent to saying it's potentially taxable, so I can't see what you're getting het up about, since I didn't say or imply they were unconditionally tax free. Will Sir kindly aim his varifocals at the "if" in "They are if...".