Are temp rezzed structures allowed?

Temp rezzers have a place...to create schools of fish, or a field of grasses, for example. [...]

They have no business being used to "get around" parcel prim limits, especially for structures...because ultimately, they steal prims and script time from everyone else in the sim.

Yes it is having it both ways. Shoals of fish and areas of grass are intended to stay there all the time. There is no difference between temp rezzing them and temp rezzing a building. The fact that one is (often) prettier than the other is irrelevant, because they are both temp rezzed for the purpose of circumventing the normal prim allowance - which, incidentally, is allowed.

Yep. Definitely put in a report on it. It's abuse - plain and simple.

Is that an opinion or is it something you've seen in the ToS? If you've seen it somewhere, please share - otherwise it's just your opinion, which isn't reflected in the ToS and, therefore, doesn't count.

Disturbing the Peace
Every Resident has a right to live their Second Life. Disrupting scheduled events, repeated transmission of undesired advertising content, the use of repetitive sounds, following or self-spawning items, or other objects that intentionally slow server performance or inhibit another Resident's ability to enjoy Second Life are examples of Disturbing the Peace.

~Temp on Rez~

You may have heard of these. They are marketed as a way to go over your prim limits with "free" prims. Temporary prims are anything but free. They are actually quite expensive when not used properly. They are prims that disappear after a minute or so and don't count against your primcount, and they are intended to be used for things such as single prim physical bullets to be rezzed and disappear quickly on their own. They were NEVER meant to be used in a way that simulates normal prims or complex objects.

Here is the problem with this sort of misuse: It takes just as much effort for the server to rez a temporary prim as it does to rez a normal prim. The server also has to go through the effort of removing the prims, so it actually takes double the effort. The more prims that are being rezzed, the more effort required by the server. When temporary prims are rezzed on a continuous loop by a script, they can (and usually do) create an enormous burden on the server. People have tried to make this less noticeable through techniques like staggering the rez time to avoid 'lag spikes'. These are parlor tricks at best in an attempt to hide the problem rather than deal with it. You get less noticeable dips in FPS and Time Dilation, but the overall effect is the same... they add significantly to lag in the region for everybody.

You can identify Temp on Rez is being used in your region by noting an constant fluctuation in the Objects number in the Statistics Bar. This is especially true if the region is otherwise empty. It may coincide with a periodic dip in FPS and Time Dilation, but not always. If your region is laggy and your suspect this is the reason, please submit a support ticket if you are on the mainland and we can investigate. If you are on a private estate, please contact the island owner or an estate manager.

-Chiyo Linden

It's abuse of region resources, probably covered under community standards #6:

I will say that talking to the neighbor first might be a good move, though. It's almost always best to try to settle things amongst ourselves first. But if that fails, you do have precedent to fall back on.

I also found this - apparently it's from a notecard that Chiyo Linden made up helping people know what to do in the case where a temp-rezzer is involved:

As Meade points out, the complaint is covered by the "Disturbing the Peace" clause and are enforced on the mainland through a trouble ticket. They won't do anything about it on an estate island (primarily because that's not their land to police in this way) but none of the estate owners I know of would let it happen if they were to know it it going on.