There is no such rule (" more than $1500 in excess of the scholarship").
What you may have read about is the rule that certain people, who can be claimed as a dependent, must file a tax return if they have unearned income over $1050. Although taxable scholarship is technically unearned income for some tax purposes, it is treated as earned income when calculating a dependent's standard deduction (earned income + $350). So, with $3000 of taxable scholarship income, your student's standard deduction is $3350. He does not need to file as he has no net taxable income ($3000 - 3350 = less than 0).
More at your other post: https://ttlc.intuit.com/community/college-education/discussion/re-everything-is-described-here-https...
