No a PMI is not a compensation event in its own right.
If a Project Manager is instructing something that they know IS a compensation event, then at the time of giving the instruction they should state that this event is a compensation event and request a quotation under clause 61.1.
If a Contractor receives an instruction that they believe is a compensation event then they could notify under clause 61.3 that they believe it is a compensation event and await agreement (or otherwise) form the Project Manager that they agree it is, and then to invite the quotation.
There are numerous instructions that you could give that would not give rise to a compensation event. you instruct them to submit a revised programme - which clause 32.2 allows you to do. You could instruct for a person to be removed from site e.g for a reason that is safety related. You could be instructing them to do something that the Works Information already states is their liability. None of these will give rise to a compensation event. Clause 27.3 gives you the power to the Project manager to instruct anything in accordance with the contract. Elsewhere in the contract will sort out whose liability that is.