No. If it were singular the verb would be chooses, not choose. Read the sentence again. If individuals choose, as opposed to if an individual chooses.

EDIT: Actually, in this specific example they used "can," which overrides the plural / singular distinction on the verb "choose," making it an infinitive regardless if the subject is singular or plural. ("We can choose. He can choose. I can choose. They can choose." etc...) Nevertheless, my point stands: The subject of the sentence is the word individuals, which is plural. They used "they" to refer to "individuals."

And to clarify, I agree 100% that singular they is a common usage that has been correct for centuries. You just picked a bad example because in their second sentence the "they" was referring to "individuals," which is plural, not singular. Thus it was not an example of singular they.