I think the main problem is that the weak eMudhra intermediates were cross-signed by Sectigo. Certificate revokations are needed to handle this correctly.
Dropping the Sectigo root along with the eMudhra root is the easy and safe solution, and maybe this is what Apple should have done (it’s the workaround they recommend!). But it means that some small percentage of certificates that are fine won’t be accepted.
Dropping the Sectigo root along with the eMudhra root is the easy and safe solution, and maybe this is what Apple should have done (it’s the workaround they recommend!). But it means that some small percentage of certificates that are fine won’t be accepted.