When Corona for 4d was quite new, I basically begged Rebusfarm to install the plugin.
Renderfarms usually wait until they're sure that the new versions of no matter what plugin they install works properly.
They can't afford people who spent a lot on render credits to get broken renders etc. This wouldn't be good for anyone. The tech guys would have to work more. people with deadlines complaining or wanting their money back.
If I owned a render farm, I'd also make sure everything that is installed is working properly or can be easily fixed. There's no sense in installing experimental releases and I highly doubt that you can find another farm that would do that.
They often are quite open to suggestions and are trying new plugins or releases but in the end, it depends on how satisfied they are with the performance of that build on their machines and is ultimately up to their judgment, what and when they can offer it as a service.