How could the tomato plant’s response to being eaten by a hornworm caterpillar be described as a function of homeostasis?

Yes

Explanation:

This can be explained with the concept of induced resistance. it is the ability of a plant to respond the certain chemical released from the damaged body parts,The diffusion of the chemical stimulates all other plants parts and other plants to be less tasty and therefore not pleasant to eat. Thus the more the extent of damage to the plant,the higher the volume of chemicals released and therefore the less tasty the plants and lower the damages-negative feedback mechanisms. Since this restored the plants to relatively constant internal environments,this is homeostasis.

Hornworm caterpillar damages tomatoes plants leaves,leaving holes.When a tomato plant is eaten,it releases chemical substance called methyl jasmonate. The latter would be received by adjacent plants parts or other tomato plants. The receptive tomatoes plants therefore becomes less tasty. Hence the caterpillar after destroying  the initial part of the tomato plants would not be able to continue with the feeding and therefore feed on one another leading to their death,turning them to cannibal caterpillars.

Since in an attempt to maintain the relatively constant internal environment plant releases methyl jasmonate to prevent futher damage and therefore ensures stability of the plant.

atp is used for energy.