He was in the CIA and upset that "several people were disturbed" by the call, and that it was placed in a secret database. However, apparently that is something that the Trump Administration has been doing due to leaks (like the whistle blower's leak). The transcript was composed by people actually in the room when the call was made, unlike the whistle blower's unsubstantiated complaint.
In a trial the whistle blower's entire complaint would be considered inadmissible hearsay. The only reason to file it is to attempt to then find substantiation elsewhere. There is an expression for legal actions such as this: fishing expedition.
Treating it with any more seriousness than that is just absurd.
ἡ δὲ κἀκ τριῶν τρυπημάτων ἐργαζομένη ἐνεκάλει τῇ φύσει, δυσφορουμένη, ὅτι δὴ μὴ καὶ τοὺς τιτθοὺς αὐτῇ εὐρύτερον ἢ νῦν εἰσι τρυπώη, ὅπως καὶ ἄλλην ἐνταῦθα μίξιν ἐπιτεχνᾶσθαι δυνατὴ εἴη. – Procopius
Ummaka qinnassa nīk!
*MySmiley*