I interpret the tweet not as blaming staffing for this gaffe so much as asserting how loosey-goosey everything about Trump living in MAL is, and that its attendant lack of proper hiring of staff and vetting of guests are symptoms that lead to situations like this.
Of course, the tweet also labors under the conceit that, were vetting and staffing both up to snuff, Trump would never have hosted Fuentes in the first place which, in the most generous way I can put this, I’m not so sure would have been the case.