This question was asked on the official Q&A forum…
If a robot drops a skyrise section somewhere on the field, but it’s not on that alliance’s protected tiles, can an opposing robot pick it up and score it on their own skyrise?
This has already been answered by Karthik. I would bet Karthik is going to kindly ask you to search the forum so that you don’t re-ask questions that already have answers The answer is Yes. You can pick it up and use it.
To clarify for some people, if an opponent team drops their skyrise section, and you mange to get over there and grab it off the ground without touching anything illegal, and can stack it on your side, it is legal. But the chances of you getting over to the other side before your alliance picks it back up is highly unlikely. Plus it would be a waste of time when you have skyrise sections on your side to begin with. So, if you have already stacked all seven sections, and happen to see your opponents drop their skyrise, then it would be beneficial to your team to go get it and stack it, or just keep it from your alliance.
The answer is Yes. You can pick it up and use it.