I think you may have misunderstood the situation I'm outlining:

1. Developer A writes some software.

2. Developer B licenses that software from Developer A, under the terms that (for instance) it only be used internally by Developer B and not disclosed.

3. Developer B makes modifications to that software and uses it as part of the implementation of a video game server.

4. Developer B goes bankrupt.

Under this proposed law, Developer B would be obligated to release the modified software, breaching their agreement with Developer A and potentially causing them financial harm.

For new games, they would know from the beginning that they’ll need to release the server software eventually, so they wouldn’t be able to agree with those terms