This is bullshit.
Facts:
a) SES is a pay grade for the most senior civil servants
b) These people should be loyal Americans who will serve regardless of the party in power
c) Many of these people are expected to spend their entire career in the civil service
d) Many were promoted into SES from lower pay grades
And now the things which need to be fixed, but are don't make the SES bad per se.
e) previous administrations were not good at vetting people entering SES
f) The Obama admin actively tried to stack the deck of SES by bringing in as many loyalists as possible
g) Many SES members, have a private out-of-government organization which is uncontrolled. This should not be allowed because it can evolve into a political lobbying force
h) Nobody has yet come up with a good way to vet people for such roles to ensure that, first and foremost, they will faitfully serve the constitution, and not the party in power.
So SES is not evil. It have just been infiltrated by evil people, like most other organizations that have some kind of leverage. It needs some cleaning and restructuring but many of the people are just fine.