The problem with just shipping AI model weights is that they run up against the issue of point 2 of the OSD:

The program must include source code, and must allow distribution in source code as well as compiled form. Where some form of a product is not distributed with source code, there must be a well-publicized means of obtaining the source code for no more than a reasonable reproduction cost, preferably downloading via the Internet without charge. The source code must be the preferred form in which a programmer would modify the program. Deliberately obfuscated source code is not allowed. Intermediate forms such as the output of a preprocessor or translator are not allowed.

AI models can’t be distributed purely as source because they are pre-trained. It’s the same as distributing pre-compiled binaries.

It’s the entire reason the OSAID exists:

1. The OSD doesn’t fit because it requires you distribute the source code in a non-preprocessed manner.
2. AIs can’t necessarily distribute the training data alongside the code that trains the model, so in order to help bridge the gap the OSI made the OSAID - as long as you fully document the way you trained the model so that somebody that has access to the training data you used can make a mostly similar set of weights, you fall within the OSAID