The Currency Shortcut

No. He has no loggable simulated instrument time in those flights, so the experience does not count.

• Logging standard: a pilot may log instrument time only for flight time conducted solely by reference to instruments in actual or simulated instrument conditions. Without a view-limiting device there are no simulated instrument conditions, so the time and the approaches flown are not creditable toward experience - regardless of how the remarks are written.
• Recency standard: the six-month experience requirement is six instrument approaches, holding procedures, and intercepting/tracking courses, all in actual or simulated instrument conditions in the appropriate category of aircraft, within the six calendar months preceding the month of flight. His only candidate entries fail at the logging step, so all six approaches fall away.
• Consequence: he is not current and may not act as pilot in command under IFR. The route back is an instrument proficiency check given by an authorized instructor - not a logbook signature.

Note the distinction he is missing: currency is a legal recency record; proficiency is a demonstrated skill. You cannot issue the first without the second, and you cannot issue either by endorsement alone.

Content:

• A ground portion covering the regulatory and procedural knowledge areas - alternates, fuel, lost communications, approach minimums, departure and arrival procedures, and the airplane's equipment.
• A flight portion conducted to the instrument rating standards and covering the required task areas: at least the required number of approaches (including one flown without reference to the primary attitude/heading instruments), a partial-panel scenario, holding, intercepting and tracking, a missed approach, unusual attitude recovery, and a circling approach if circling is to be authorized.
• The check is pass/fail as a whole. You do not "average" it, and you cannot award partial credit for a good ground session.

Documentation:

• Enter the flight in his logbook in the normal way; you may log the flight time and instrument time you actually flew.
• Sign the logbook at the time of the check with the endorsement recording that you gave the instrument proficiency check, the date, and your certificate number.
• Keep your own record of the endorsement - instructors must retain a record of endorsements given for three years - plus your training notes. If he later claims an endorsement he did not earn, that record is your defense.

Do not pre-sign, do not back-date, and do not write "IPC complete" before you have flown it.

Do not endorse. Fly the airplane first, then have the conversation.

1. Take the controls and stabilize the airplane - altitude, heading, and a clearance you both understand. Terminate the approach work.
2. Stop the check. When a required task is not met, the IPC is not satisfactorily accomplished. There is no "mostly passed" and no instructor discretion to waive a task; your signature would be a false certification and would put him in an IFR cockpit without the skills to fly it.
3. Log what actually happened. Record the training and the instrument time flown, and note in your own record that the proficiency check was not completed. If he wants the logbook entry of the training, that is fine; the IPC endorsement is not.
4. Tell him plainly what he needs: additional dual covering partial-panel attitude control and missed approach procedures, then a full re-check. Offer dates.
5. Address tomorrow's trip directly. The hard answer - he cannot legally fly IFR. A VFR flight, or a different plan, is his call; your obligation is to make the situation unambiguous so he cannot later say he understood otherwise.

Experience is not evidence of proficiency in a task he has not practiced in eight months. The twenty years is exactly why he will be convincing and exactly why the failure matters.