Currently, when we transition to rollback we clear out the majority committed snapshot value maintained in replication coordinator and by the WT engine's snapshot manager. And, I think that's really unnecessary due to below points.
1) Rollback common point can only be >= majority committed snapshot value (applies both to EMRC false and true)
2) For EMRC= true case, when recoverToStableTimestamp() is called no other read or write operations can be performed as recoverToStableTimestamp is performed under global X lock

Also, the comment mentioned here looks stale as things have changed a lot after this commit (which drops the usage of named snapshots). ( Note: as part of this ticket we should also update _dropAllSnapshots_inlock() to something what it actually does - clearMajorityCommittedTimestamp()).