Yes,it is true that the woman is a self-appointed tourist guide because she is harassing the speaker to make use of her services, even though her goal is to get rid of her. Her determination is seen in the fact that she hobbles after him and goes to the point of stopping him by tightening her grip on his shirt. The speaker is getting more and more irritated, and he wants to get rid of her by being firm in rejecting her offer. If we equate the relationship between the speaker and the old lady, we see that it’s not much different from the exchange that’s going on between the tourist and the beggar.
The beggars are often following people around, harassing them with a demand for alms. But the difference is that if the tour guides sell their services, the beggars don’t. This immediately creates a world of disparity between the two groups of people. It shows that even though tour guides can be as irritating as beggars, they are self-respecting people.