If it is in a keg then go for it. If it is in bottles then I probably wouldn't because you risk a lot of oxidation when getting the beer back into a fermenter.
Once you've warmed it up and released the CO2 (and allowed it time to equilibrate - use something like an airlock/blowoff tube on the keg to keep the CO2 coming out until it equilibrates), then the carbonation level will be pretty much the same as the residual carbonation from fermentation. It shouldn't really be any different to adding brett at the end of fermentation then.
when i make a bad beer i do this but i dont warm it or anything i just put it in. now i will say my sours have taken some time(years) to really get good but i always thought it took a long time to do so but im no funk brewing expert. next one i do maybe ill warm it first