How does Transport via Plant work?

I recently had a discussion with a Player about the wording of this Spell.

As far as I understand it, this spell can teleport a creature or player over a infinite distance (as long as you have been at the place and it is on the same plane of existence).

His interpretation is that (as a druid), he can make a plant via magic and either push a creature into the plant or create the plant beneath them. Then, when he casts this spell and the creature only touches the plant, it will be teleported, and it loses 5ft of movement distance.

I think that after casting the spell, a creature must walk into the plant by using 5ft of movement (creature can be charmed, hypnotized, stupid or whatever) and then gets teleported. A creature does not lose movement distance by being pushed, therefore the spell would not teleport it.

My problem with the first interpretation is, that this spell makes any boss fight basically a contest to push the enemy to transport them far away, therefore making the fight itself useless/instantly over. What is your interpretation?