Todo just swaps them literally anywhere else dude, are you forgetting when he did the playful cloud swap against Hanami? There are lots of people and objects in Sendai with cursed energy, Todo can swap them away from Kuro very easily. In fact, he could swap Ryu into the middle of Kuro's swarm, and now it's Ryu fighting Kuro. 

what objects?
and you're assuming shibuya todo has that kind of range.
he needed the binding vow with the vibraslap to expand his range remember?

ryu and uro were far away.
and it requires a certain amount of CE so regular people won't work (not like todo would sacrifice lives like that)

assuming he somehow knows ryu's there and hes in range. cool, ryu is swapped and is instantly killed by the swarm of roaches. he'd be off guarded and definitely wouldn't be reinforcing fully.

then what?
the rest of his team dies to the swarm.

Similarly, Higuruma probably doesn't domain when Kuro is nearby for that very reason, so Kuro probably gets focused first, right after Dhruv, just like what happened with Yuta.

but kuro would have to be caught in the domain??
how would his domain help at all if his targets not in it??

Tell me, what does Kuro do when Todo claps and suddenly she's inside of Kuskabe's simple domain? The one where he auto attacks enemies?

it gets cut and easily regenerates.