my very humble opinion is that this guy was dead much less than 6 months. his tattoos were that well preserved and they think he might have been dead 2 yrs? no way.
according to research, tattoos can stay until stage 3 decomp. and even in some cases after. so yes, while florida environs probably accelerate decomp in general, not unneccessarily true that tattoos wouldn't exist.
NAMUS does also indicate they found skeletal remains..and images do suggest that only parts of tattoo were remaining.
I am not an expert, JMHO, but I would think they have some rationale for saying 6 months to 2 years...maybe extrinuating circumstances/conditions at the site suggest slower rate of decomp?