Mostly, the efforts are toward managed access rather than secrecy. Getting to the tree requires significant intent and commitment. And while it's awesome, the tree is somewhat unspectacular relative to nearby [1] alternatives with better access: Yosemite, Kings Canyon, Sequoia, and Death Valley National Parks. Getting there even requires a detour from US395 and US395 is not a high travel highway...nothing of note to the east and the Sierra Nevada to the west. It's about 250 miles of second class roads from Los Angeles, Reno, and Los Vegas.
Currently, the road to the grove is closed for the season. Weather also keeps people away.
[1]: at the scale of the western US.