I feel like the way it was drawn, the necktie gave a more “child dressing up in daddy’s work-clothes” feel. Mostly due to the, quite frankly, huge knot in the tie and how loose Phil’s collar is. This was emphasized by the bow tie being half the size of the knot alone, alongside how the bow tie covers the gap in Phil’s collar, while the tie is low enough to simply put emphasis on it.

I went back to look at Shiden’s hearing to see how the tie was done there, and the only page with a clearly visible tie I could find was page 2506, which also had an impressively large knot. All the other’s, if the Senator was even wearing a tie during the proceedings, were hidden by jackets done up so high that even the knot wasn’t clearly visible.
https://www.yoshsaga.com/comic/2506/