What they have said to you conforms with ICAO requirments.
I have no problem with an instructor getting 100% credit for the flight time they spend in the RHS, they are the PIC, they are the ones responsible for the safe conduct of the flight.
Similar is the long haul skipper of say a 744, when they go off to his crew bunk, they are still logging PIC time, they are not even physically in the cockpit or in physical control of the aircraft, but if something were to go wrong they are still the person in charge.
This is pretty well much the ICAO requirements .....
(1) For the purposes of paragraph 5.165 (1) (f), a person's aeronautical experience must consist of at least 1,500 hours of flight time that includes 750 hours as pilot of a registered aeroplane, or a recognised aeroplane.
(2) The 750 hours must include:
(a) at least 250 hours of flight time as pilot in command; and
(b) at least 200 hours of cross-country flight time; and
(c) at least 75 hours of instrument flight time; and
(d) at least 100 hours of flight time at night.
(3) For the purposes of paragraph (2) (b), the cross-country flight time must include at least 100 hours as pilot in command or pilot acting in command under supervision.
(4) The balance of the 1,500 hours of flight time must consist of any 1 or more of the following:
(a) not more than 750 hours of flight time as pilot of a registered aeroplane, or a recognised aeroplane;
(b) not more than 750 hours of recognised flight time as pilot of:
(i) a powered aircraft; or
(ii) a glider (other than a hang glider);
(c) not more than 200 hours of flight time as a flight engineer or a flight navigator calculated in accordance with subregulation 5.173 (7) and the balance of the flight time under paragraph (a) or (b).
(1) For the purposes of subregulation 5.172 (2), the same flight time may be counted towards as many of paragraphs 5.172 (2) (a), (b), (c) and (d) as describe the flight time.
(2) For the purposes of paragraph 5.172 (2) (a), the flight time as pilot in command may include up to 150 hours as pilot acting in command under supervision.
(3) For the purposes of paragraph 5.172 (2) (c), not more than 30 hours of instrument ground time may be substituted for an equal amount of the 75 hours of instrument flight time.
(4) For the purposes of subregulation 5.172 (4), not more than 100 hours in an approved synthetic flight trainer may be substituted for an equal amount of the flight time required under subregulation 5.172 (4).
(5) The 100 hours mentioned in subregulation (4) must not include more than 25 hours in a synthetic flight trainer that is not a flight simulator.
(6) CAA may approve a synthetic flight trainer for the purposes of subregulation (4).
(7) In calculating the hours of flight time for the purposes of paragraph 5.172 (4) (c):
(a) each 3 hours of flight engineer time in regular public transport operations is counted as 1 hour of flight time; and
(b) each 4 hours of flight navigator time in regular public transport operations is counted as 1 hour of flight time.
(8) Each period of flight time flown by a person as a pilot, but not flown:
(a) as pilot in command; or
(b) as pilot acting in command under supervision; or
(c) in dual flying;
must be halved in calculating the person's flight time for the purposes of regulation 5.172.