Can you share the input file for reference ? So those are 2 GAPUNI elements (with spring-like symbols) attached to a common rigid body reference node ?
Regarding the compression-only constraint, it would be also helpful to have an option to invert its direction: Tension-only constraint
Perhaps there could be a compression-only spring so that the user could apply it like Point Spring to selected nodes (although, currently Point Spring is grounded so I guess two-node springs would need to be added first).