What level of pilot are they? While spin training can be good, do you really want a student or private pilot going out and doing them by themselves? Besides that you may not be legal. Ac 61-67c hits on it as well as 91.307(c). If it is not for a certification or rating as excemted in 91.307(d), you need a chute.
AC 61-67C - STALL AND SPIN AWARENESS TRAINING
301. SPIN TRAINING AND PARACHUTES. Part 91, section 91.307(c), prohibits the pilot of a civil aircraft from executing any intentional maneuver that exceeds 60° of bank relative to the horizon, or exceeds 30° noseup or nosedown attitude relative to the horizon, unless an approved parachute is worn by each occupant (other than a crewmember). Section 91.307(d) states, in pertinent part, that section 91.307(c) does not apply to flight tests for a pilot certificate or rating; or spins and other flight maneuvers required by the regulations for any certificate or rating when given by a certified flight instructor (CFI) or an airline transport pilot (ATP) instructing in accordance with section 61.167.
a. Section 61.183(i) requires an applicant for a flight instructor certificate or rating to receive flight training in stall awareness, spin entry, spins,- and spin recovery procedures. The applicant must also possess and demonstrate instructional proficiency in these areas to receive the certificate or rating.
b. Because spin entry, spins, and spin recovery are required for a flight instructor certificate or rating, a person receiving instruction from a CFI (or an ATP instructing in accordance with section 61.167) need not wear an approved parachute while instruction is being provided in these maneuvers. This provision applies regardless of the certificate or rating for which the person is receiving training and also if the person is receiving instruction that is not being provided for the purpose of obtaining any additional certificate or rating. The instructor providing the training is also not required to wear an approved parachute while providing this flight training.
§ 91.307
(c) Unless each occupant of the aircraft is wearing an approved parachute, no pilot of a civil aircraft carrying any person (other than a crewmember) may execute any intentional maneuver that exceeds -
(1) A bank of 60° relative to the horizon; or
(2) A nose-up or nose-down attitude of 30° relative to the horizon.
(d) Paragraph (c) of this section does not apply to -
(1) Flight tests for pilot certification or rating; or
(2) Spins and other flight maneuvers required by the regulations for any certificate or rating when given by -
(i) A certificated flight instructor; or
(ii) An airline transport pilot instructing in accordance with § 61.67 of this chapter.