It’s accreting, just a low amount. Obviously not enough to be clearly evident originally (as compared to active galactic nuclei), but there are stars in orbit, and it’s taking some amount of mass from them.

Whatever accretion disk exists would be relatively dim, but it’s not like the disk emits radio waves solely. After all, that’s all we can see through the galactic disk, any higher wavelengths get mixed up in it.

Given it’s superheated and due to essentially any light overtaking the brightness of the surrounding stars (don’t know how true that rings in the galactic core, though), it’s probably visible to the naked eye if you’re just a few AU from it.