Well sometimes a small critter can create a lot of havoc, so don;t judge them by their size.....But they are considered reef safe and easy going fish. I have never seen mention of the yellow clown goby bothering corals of any type, but I do see references of the citron and green and black ones possibly nipping the corals. IIRC the yellow is the smallest of the species.
I have a need for two yellow myself, but do not see them listed on SWF, and my local lfs will not order them for some reason or other, they say they have to buy a set quanity of them, and they never have much of a call for them, so they will not stock them. ***** had 4 of them and when I went to get two yesterday, three were stuck in thre filter strainer, and the 4th was all puffy and blistered looking. It would be 2 more weeks until ***** got in a customer order, so I may just do my first mail order or purchase online of fish today.