HMC412B near-DC operation operation


I am using the HMC412 in a near-DC (down to a few 100 Hz) manner and I wish to drive a balun (simple transformer) to pull the IF off-board in a differential manner. One thing I see in the datasheet is this warning:

"For operation to DC, this pin must not source/sink more than 6 mA of current or die non-funtion and possible die failure will result."

Why is this the case? Is it the ESD protection diodes?

Will it be too risky to have a transformer as the load?