Scale of the disaster: anectodical
Sad. I love a good planet-shattering assumption as much as the next guy, but this won't do. I blame your lack of ambition. Yes, the surface of the sun is hot, but it's not that hot. You don't get really get to any of the fun stuff; you're nowhere near the temperature to have nuclear fusion effects, you're not even close to a temperature where you could turn the air to a plasma (you would need to go over 10000K for that). Where is your sense of fun? In fact, typical gases that you'd use on a gas stove (butane, propane, natural gas) burn at around 2000K, which is only a 3rd of the way to your temperature (even tho it's misleading to present a ratio since most temperature-dependent trends are nonlinear)
The problems are essentially going to come from the radiated heat. Let's estimate it (roughly) to get a ballpark idea of the damage. To do that, rather than calculating absolute values (which would be challenging anyway cause you don't give enough data), we will compare it to our good old gas stove:
It will pretty much only burn your house, and maybe a few neighbors but they probably deserved it
Ok, so, my stove burns at 2000K. Sun-boy is at 6000K. That's 3-times as much, and per the <PERSON>-Boltzmann law, the radiated power varies as the $T^4$, so, at equal surface areas and emissivity, Sun-boy would radiate $3^4=81$ times as much heat. Ok, but he is also bigger. In fact, the body surface area of an adult is around 2m2 (https://en.wikipedia.org/wiki/Body_surface_area). Taking some quick measurements on my stove, I estimate that the flame surface can't exceed 0.03m2. 912
So Sun-guy's surface is about 70 times larger than my stove's flame. Assuming equal emissivities, we can conclude that
$$\text{Sun-guy will radiate roughly }70*81=5670\text{ times as much heat as my stove}$$
According to the inverse-square law, if I stand $\sqrt{5670}=73$m away, I will receive as much heat as if I was standing 1m away from my stove. I can definitely get half a meter away from my stove without feeling pain, so I'd probably still be fine some 30m away from Sun-dude. How disappointing.
It still melts everything it touches tho, isn't that scary?
Well not really. It just takes care of your problem for you really, by burying it 6 feet under. Quite fast, in fact. Some quick and dirty estimates with a latent heat of fusion around 200kJ/kg tell me that you could liquify around 70kg of rock per second (not counting the time to heat it up to fusion temperature, and not considering the fact that you will spend some of that energy further vaporizing the melted rocks). Standing still, you will probably be gone in a matter of tens of seconds to a few minutes. If <PERSON> can walk tho, it might actually be feasible to remain on top, since you don't melt the ground that fast (depending on assumptions, you might be sinking from 1 to 20cm/s)
I lack the geology knowledge to tell if a white-hot mass sinking into the ground will cause problems down the line, but I doubt it, seeing the temperature of the interior of the earth. Just in case, I wouldn't stand close to the crater. It is likely going to get trigger happy with all that melted rock getting stirred up with pressurized bubbles
In summary, the damage you will do will be very localized (you will set a couple house on fire), and then the problem should take care of itself
* ed by <PERSON>: sorry for vandalizing, I can't comment, your answer is great and just one small suggestion, pay attencion to soy boy density and molten rock density he will float, so he so sad that he even can't dive to the core of the planet. As evaporating ability 70kg easily can be slashed 4x (only half of sun guy works on evaporating, and latent heat of evaporation another 2x at least) all in all sinking potencial is quite limited. Great answer, sorry can't upvote either, due old browser. 912