Instinctive behavior, or not?

The two mixed-breed rabbits that share our living quarters have had good litter habits. The spayed doe has been perfect about doing both #1 and #2 on paper in an always-open dog crate. The neutered buck has been good, too, except the times he sprays when he gets excited.

Enter one pedigreed intact Flemish Giant buck, assigned to his own quarters, separated from the others with a substantial gate.

Immediately, our two old-timers started doing nearly all their pooping in front of the Flemmie's gate. The doe will even take an occasional whiz in front of him, too. (He likes to lay down leaning against the gate.)

Rabbit gurus who understand bunny instinctive behavior, can you explain what's going on? I'm guessing it is some sort of rabbit display, communication or courting; but, could be far from wrong.

It's no biggie. After neutering our expensive pedigreed breeding stock and changing it into a less valuable pet, the living arrangements are likely to change; but, in the meantime I'm curious.

Your rabbits are marking their territory, letting the new rabbit know that they don't accept him.

Very good! Of course. That's the most plausible explanation, so far. Thank you.

For sure, they've shown zero sign of acceptance; there is obvious antagonism on both sides between them through that gate.