Just tested in a Mamba, no issues using guardian hull and module reinforcement packages inside the Leigong Titan maelstrom. So you can have that extra caustic resistance if you can afford the power draw. (personally, my Mamba power draw margins are razor thin, and I had to do a lot of priority massaging, and deactivation of 2xcaustic sink and 1xtp neutraliser once inside the maelstrom to allow my weapons to function.)
So those AND the guardian nanite torp pylon are exceptions to the "no guardian tech" rule.
edit: tested with a full approach to Leigong, successful pulse neut (only needed one, since mamba=fast) and 2 x 5 vent bombing runs @ 2.6mil combat bonds total. Got attacked after second run, checked modules after both runs, guardian modules still online.
So those AND the guardian nanite torp pylon are exceptions to the "no guardian tech" rule.
edit: tested with a full approach to Leigong, successful pulse neut (only needed one, since mamba=fast) and 2 x 5 vent bombing runs @ 2.6mil combat bonds total. Got attacked after second run, checked modules after both runs, guardian modules still online.