Angular 2 direct, make content editable only for admins

editable.directive.ts

import { AfterViewInit, Directive, ElementRef, HostListener, Input } from '@angular/core';
import { UserService } from '../shared/services/user.service';

@Directive({
  selector: '[flEditable]'
})

export class EditableDirective implements AfterViewInit {
  @Input('endpoint') endpoint;

  constructor(private el: ElementRef, private userService: UserService) { }

  ngAfterViewInit(): void {
    this.userService.isAdmin$
      .subscribe(x => this.el.nativeElement.contentEditable = x);
  }

  @HostListener('blur')
  log() {
    this.endpoint(this.el.nativeElement.innerText).subscribe();
  }
}

// Usage:
//                          <span class="print-hidden" flEditable
//                                 [endpoint]="updateBulletinSubTitle">{{bulletin.subtitle}}</span>