If SCOM, or any application, is using the modern drivers, MultiSubnetFailover is only recommended, not required. The newer drivers for .NET, ODBC, OleDb and JDBC have implemented a feature Transparent Network IP Resolution that enables connectivity to multi-subnet clusters and to clusters using Distributed Network Names without specifying MultiSubnetFailover.
.NET Framework SqlClient
Under this new behavior, which is enabled by default, clients will only experience a very brief delay when connecting to a multi-IP SQL Server endpoint, if the first-returned IP is not online. Under the old behavior the clients waited for 20sec or so trying to connect to the first IP, which typically caused an error in the client app.
So if you can find a way to set MultiSubnetFailvoer in SCOM, do it. But if not you should be fine, and there's no need to turn off RegisterAllProvidersIP on the AG Listener's Client Access Point, which was the previous mitigation for this issue.