If someone with skills X (where depending on your knowledge and precautions, X can range from script kiddie to nation state) is after you specifically, you can only make their job harder, but unless you are very serious about security, you’ll probably get pwned.
If you want general security, you can probably take it as given that someone checked the Signal build to be the one that the source is available for, and that no one intercepted just your download. But you still have to take some parts on faith, always, unless you build your own CPU and continue from there.
If someone with skills X (where depending on your knowledge and precautions, X can range from script kiddie to nation state) is after you specifically, you can only make their job harder, but unless you are very serious about security, you’ll probably get pwned.
If you want general security, you can probably take it as given that someone checked the Signal build to be the one that the source is available for, and that no one intercepted just your download. But you still have to take some parts on faith, always, unless you build your own CPU and continue from there.