We do the same for riding ziplines or taking jump pads too. Yes, they are Ultimates - but they are deployed abilities in the world and we consider their utility differently than how we control
You can neither heal nor shoot well on ziplines. You can barely shoot on jumppads, but you can heal. Those are ultimates.
Now horizon's gravity lift is a tactical and she can heal, shoot and ult during it and use it multiple times? Don't you think that's a bit misbalanced?
if we limited your ability to heal, use weapons, throw grenades/abilities... the lift would feel pretty one dimensional.
Just as one-dimensional as any other movement tactical is. Taking height with your entire team is strong enough alone.
Allowing the player to use weapons/meds or abilities, gives agency and play potential not just to Horizon, but anyone who uses the lift - making it a dynamic element on the field....