I really don't see the resemblance to the Jackson Chameleon aside from the horns. Given that anybody can write/edit a wiki site, I would need a more concrete (e.g. from the developer) explanation before I believed any one argument.
If you read it more closely, you'd notice that the wiki has references to specific in-game dialogue, namely:
http://fallout.wikia.com/wiki/Ocjoseph.msg
{146}{}{Well, let's see... Deathclaws appear to be mutated Jackson's Chameleons, the horned variety.
There are a lot of similarities still present, but an even greater number of differences. The mutation
factor is quite high. This species is highly intelligent, about the equivalent of an eight-year-old,
with some individuals reaching human normal level. Their learning capacity is very high and they are
capable of abstract thought and reasoning.}
(He's speaking about the ones further mutated by the Enclave).
Information about them being genetically engineered and not a natural mutation comes from the official Fallout 2 guide, written by Matt Norton, the lead designer of FO2.