I guess some fan forum had been debating it and the showrunner felt the need to explicitly state it. I haven't watched any of this season yet, but I always thought it was pretty obvious.

https://www.yahoo.com/entertainment/boys-showrunner-confirms-homelander-trump-192140015.html

I read the books a couple of years ago but I think they came out during Obama's administration. So we didn't quite have anyone to compare to Homelander back then. I don't know how the comic's characterization would hold up when closely compared to the show.