The repo would be a trade secret and downloading it could potentially be construed as misappropriation of such. However, I know of no case in which someone decided to sue every individual who downloaded a leak out of curiosity. Usually you'd only bother for large businesses that could actually gain a competitive advantage from that data.
Of course, the flip side of that is that anyone who has ever touched the leak is persona non grata in that industry. So if you're interested in learning how QBasic works, and you ever want to touch anything that interprets scripting code, don't touch those leaks.
FWIW disassembling QBasic (instead of obtaining leaked source) would be an absolute defense against a trade secret claim, but in terms of copyright you now have "access", and need to avoid "substantial similarity" in any source code you write. You aren't strictly-speaking "tainted" (clean-room is not a legal requirement), but if someone actually sued you for copying QBasic you'd better have a good legal argument for why every line of your code does not infringe upon the code you disassembled.
Of course, the flip side of that is that anyone who has ever touched the leak is persona non grata in that industry. So if you're interested in learning how QBasic works, and you ever want to touch anything that interprets scripting code, don't touch those leaks.
FWIW disassembling QBasic (instead of obtaining leaked source) would be an absolute defense against a trade secret claim, but in terms of copyright you now have "access", and need to avoid "substantial similarity" in any source code you write. You aren't strictly-speaking "tainted" (clean-room is not a legal requirement), but if someone actually sued you for copying QBasic you'd better have a good legal argument for why every line of your code does not infringe upon the code you disassembled.