The son is not likely to be anyone's tax dependent. Although his income is not taxable, he cannot provide more than half of his own support. $30,179 is not a small amount of money, and most likely that income provides more than half of his support. That would keep him from being eligible to be a dependent, even with no taxable income.
You cannot claim medical expenses for a person that isn't your dependent due to providing more than half of his/her support. You could claim the expenses if the son was a dependent in a prior year, when the services were rendered.
$14,200 is also not a small amount of money. To determine if this disabled son is a dependent, all of his support needs to be tallied (medical, housing, food, travel, etc).
You can use the Support worksheet in Publication 501:
https://www.irs.gov/publications/p501/ar02.html#en_US_2016_publink1000220886
.
