One the mayor clearly does not like him and there seems to be some history there as well so he could be a good ally through Perry and Ian, two there is Billy and stalkfap that I largely do not think Seymour could effect. Billy seems to have a lot of money as well and could easily rival Seymour., three Axel though not the greatest ally does seem to care about Lena enough that he would not just listen to Seymour unless he is an enemy.
By Perry you really mean his father. And yes, the mayor can help, while apparently not as much as he should, but at least he has some political connections and money.
Ian yes, he has ties to Victor White at the moment and is a bit about Seymour's dirty laundry regarding the use of publishers, so he can start investigating in that direction.
Lena will be easily cut off from Stalkfap, especially after Peoplegram is blocked, which will only make her account known through people she knows.
Billy? He has
some money (his father's), maybe some connections, but obviously not enough to compete with Seymour, plus based on his personality, he's probably a coward. So there's no talk of "easily rival." But he could still try to set up his own modeling agency.
Axel? Well, given his obsession with Lena just as much as Seymour's, in some paths he can help, yes. But given his opportunistic sociopathic nature, on others he might choose not his feelings, but the possibility of promotion.