That's because Litchi's air normals are in general pretty good (her j.B has good priority and range) and better than Tao's.
2D is actually pretty good since generally you can come up with two different situations:
- the Litchi player is throwing her j.B preemptively to safely get close you and to make sure he doesn't get countered by something
or
- the Litchi player goes for a deep jump-in/IAD with j.B, in that case you know when it's coming at you
in the first case after her preemptive j.B's recovery, depending on the angle you can still try a 2D or a 6a (or dash 6a if her jump won't get her too close). Don't bother IAD+airthrow, Litchi has a better airthrow than you anyway. In the second case, block/IB and counter (2a, throw, it depends if you manage to get that IB and immediately play some mixup as Litchi lands).
They may also attempt to cross you up either with her j.B (through a jump) or wither her falling/dive attack from a IAD, so be aware of it. In that case just try to block/IB. Tao's anti-air sadly ain't that great (which is why this matchup is pretty even, as Litchi controls the air better than Tao while Tao has an advantage if it's a ground vs ground game).