It wouldn't be what I call ideal for life but it should be good for 3-4 years at least. BTW, the situation is roughly the same for an Asian arowana.
They are not aggressive to non-kin tank mates, if the tank mates cannot be preyed on.
Tigs are funny fish, they lay around all day long, like 90%+, and may or may not move much in the night. I've never known about ours since I sleep at nights. But if they do need / want to move, a 6'x2.5' footprint would be way too tight for 2' tig, only good until 1'-1.5' size.