That means if H1 doesn't use EAD, then H4 can keep his(her) H4 status when he(she) uses EAD. So H4 will be ok even if the 140/485 have problem.
Actually as I know anyone can use EAD and has no problem when the 140/485 get rejected as long as he(she) maintains a nonimmigration status.The problem is most H1 holder uses EAD when he(she) can't maintain H1.