If AC started comping UA status, I would expect to see a run on their program as you guys scramble to "protect" yourselves from the possible collapse of UA and Mileage Plus. This would be a very dangerous precident for AC or any other STAR carrier to set, and would be like announcing a "run on the bank" vis a vis the viability of UA. It could also swamp Aeroplan which in 2001 had about 10K top tier SuperElites [1K], 83K Elites [PremEx] and 210K Prestiges [Premier].
AC and other STAR carriers might consider comping a non-NAmerican UA elite, on a basis such as Empress has explained: contact a sales office and guarantee a certain amount of business to AC.
Another reason such comps, particularly to Elite [SE would be highly unlikely], would be difficult for AC to rationalize is that, with STARGold status from another member carrier, one gets access on UA domestic/NAmerican flights to all the RCCs. This would be a savings of several hundred dollars a year to UA fliers who would no longer have to buy separate memberships, and thus become a substantial liability to AC since it would be billed every time such a [former UA] member used a RCC.