I see what you mean. On the other hand, why should Bitcoin Core have a monopoly on the doctrine? I am glad that there are other bitcoin clients with different policies.
What has to be clarified is whether Ocean is specifically targeting these coinjoin transactions or just happens to have a lower OP_RETURN limit.
They just happen to have that limit. Some services that rely on OP_RETURN to function can be affected here. But one has to say that relying on being able to inject arbitrary data into your tx is just shitty engineering. Other coin join services don't do this, which is MUCH better for privacy, which is the whole point.
