If you pin one of the RS422 inputs to midrail then the receiver
will "work" with a single ended input. Not to expected specs.
And you'd then probably lose the input failsafe function if that
matters, unless the "live" output is also pulled to that center
point.
You could throw true and complement out the '244 outputs
using two of the available channels, plus a preceding inversion
somewhere for one. Keep the 100 ohms cross-output termination.
Then the only thing you lose is the reverse current protection
(cold sparing etc. is compromised).