Matter existing at "low temperatures" is stable only in the first generational stage of matter. Here "low" is very relative and in this sense millions of Kelvin is still considered low temperature.
The first generation of matter is comprised of three particles: Up and Down quarks and electrons which it is no coincidence that these are the only types of matter we observe on a day-to-day basis. Note that matter quarks form bound states in three's and there are only two possible combinations with two quarks; which are known as the proton and the neutron.
Unlike chemicals, formed from numerous atoms which can occupy nearly endless collection bound states, restricted by a huge number of factors. Matter Quarks (which comprise baryons) have only one bound state called a triplet involving exactly three quarks. For all interactions, if it is energetically favorable to decay, the bond will break apart and the constituents will arrange in the lowest energy configuration possible. Quarks are no different; very energetic high mass bound states such as Xi or Sigma baryons will rapidly decay, so quick is this dissolution in fact, that only the tell-tale sign of their existence is the way their low energy constituents are observed to move into detectors within particle accelerators.
So unless there is some very bizarre unobserved physics which would allow for low-energy quarks to occupy bound states other than triplets, or a mechanism which forbids high energy bound quarks from decaying and thus occupying meta stable states, then it is simply impossible for any other stable baryons to exist.
Since we have been searching for exotic states of matter for the better part of half a century, and since the number of available interactions are so few, it is quite reasonable to assume that we would have observed any other stable baryons by now.
Possible fictional scenarios which might allow a way for physical analogs to come into play might be an event which a black hole is ripped apart. Realistically this event has never been observed and currently is theoretically impossible. However, if such an event could occur it is conceivable that massive stable baryons could emerge in a similar analogy to how stable heavy elements emerge from supernova and neutron star collisions.