Access node taxonomy through compute function

I am using a computed field in a node where taxonomy terms associated with that node influence the calculation. I have had to rewrite utility functions that extract information from the node so that they can be called from computed field's compute function. This is because in all previous cases I could take taxonomy information directly from the node but the &$node argument passed to the compute function does not contain taxonomy information.

Is it possible to change the module so that taxonomy information is available through the &$node parameter to the compute function?