i wouldn't believe that for a second, i would ask them for proof and a singed warranty that they will assume a duty of care and reimburse in case of any problem,
the problem in a rotary is not with seal compatibility its meant to inject oil, synthetic oil doesnt burn favourably and leaves a film deposit which builds overtime and will kill the engine. if they say that they use synthetic and sat that their oil is compatible with the bearing material, sealing elastomers & combustion seals used in a rotary engine. then i would call that BS as it needs to consume oil, to keep the seals compatibility has no relation to it.