"I imagine that would be more entertaining than anything, depending on who it happened to be."

There's definitely an individual or two he's sure would get a little worked up at the sight of a naked woman gardening. He's not one to get attached or even really care much about most people as individuals in general, so there's little fear of any sense of possessiveness developing on his part. Nor does he feel any particular compulsion to 'protect' her; she could do whatever she pleased, as far as Merlin's concerned.