An instruction can apply to 'any work' although this is not defined, presumably so as not to limit the scope of what can be instructed
If under a main option C (or D or E), then, depending upon what work is the subject of the instruction and how long the period of 'suspension' is for, then the issue of Disallowed Cost may apply. The most likely application is in relation to 'resources not used to Provide the Works', (Equipment and People) although this should take into account 'reasonable availability and utilisation'.
My interpretation of this Disallowed Cost clause, however, relates to the fundamental reason for a resource being on Site, rather than just a measure of efficiency, as the 'efficiency measure' is addressed by the share mechanism and the PM can also request the removal of a person.
The issue of 'fault' would be relevant to whether the matter constituted a compensation event, rather than an assessment of Disallowed Cost.