That's the beauty of paper - it allows anything to be put on it but does absolutely nothing to actually make you do whatever you promised. Those promises are, quite literally, not worth the paper they are written on.

If a Government (or TLA or whoever in power) wants some Evil Thing, a piece of paper from somewhere promising not to do Evil Things will not be a hindrance to either asking [or, depending on where, compelling] you to take part. If you have the option to decline, they will keep asking people (and increasing the financial reward) until someone agrees.

Wouldn't many programmers object to being coerced into signing a "code of moral conduct" to begin with?

Why would that matter?