Bounded projects inherit permissions from the container so users with edit access to the spreadsheet will have edit access to the code in the bounded project.

One alternative to protect the code is to move to a library. Another alternative is to create an add-on.

Bounded projects inherit permissions from the container so users with edit access to the spreadsheet will have edit access to the code in the bounded project.

One alternative to protect the code from editing is to move it to another project to be used as a library. Another alternative is to create an add-on.

References
Collaborating with Other Developers - Google Apps Script