The quick answer is yes, it's Biblical to raise support. Paul's words to the Corinthians in 1 Corinthians 9 are especially helpful. Check out his instruction in verse eleven: "If we sowed spiritual things in you, is it too much if we reap material things from you?...So also the Lord directed those who proclaim the gospel to get their living from the gospel." Thus, the Biblical mandate is that ministers of the word and prayer "get their living from the gospel."

Of course, rare exceptions apply. Even in this very passage, Paul states that he would never exercise his right to a living from the Corinthians, due to several factors. The biggest of these reasons is that Paul felt led of the Spirit that taking cash from the Corinthians would diminish his leverage for the Gospel.

As a background, major public speakers of the first century were generally paid large sums of money. In fact, to not ask for such a sum would've been taken as an indication of your relatively low worth as a speaker. Paul knew this and chose to go exactly against, so he would have better footing on which to present the Gospel to the Corinthians. Read 1 Corinthians for a sense of this.

A modern-day example of preachers of the Gospel who simply trusted God for their living and did not solicit funds is the duo of John and Charles Wesley. They simply trusted God and He providentially provided, sometimes through bags of cash literally being dropped off at their front gate.

Your son must seek God's Spirit in His word and the counsel of Spirit-led believers to determine his support model. Biblically, he's on solid ground to actively seek support.

I pray this helps...