You'll need more empirical evidence of why Long Lances needs to be restricted. If you played top tier decks against the Long Lance deck and the top tier decks were consistently unable to beat it, then you've got a problem. There's not enough data on the viability of a deck focused on Long Lances for a determination right now.
You don't want to base it on theory or else we get The Laughing Storm fiasco again. Better to see the cards play out and take action as necessary.
I have not played against a Long Lances deck yet, but from what I hear it is very abusive with Street Waif. The discard pile is often nearly empty. Even if you kill off all the Long Lances and Street Waifs, they are returned to play with To Be a Dragon(put into play from dead pile) and Recruitment(put into play from dead OR discard pile) with ease. Then Street Waif is knelt trigger its ability to reaquire these put into play events, which can then be used again in the next phase to grab any other dead or discarded Mercenary or Ally, thus allowing you to trigger Long Lances and standing the previously triggered Street Waif. Then you can trigger the Street Waif again.
If the deck is built without events like that, then you can get rid of Long Lances and Street Waif without too much worry that they will be returned to play easily. The problem is, it's not just Ambush that triggers Long Lances. It's that you have dead and discarded characters hopping into play and the ability to do this is very easy to reacquire with the Discard pile to hand recursion available. In addition to that, with To be a Dragon, Long Lances is standing the second character in that player action window.
Now I don't know if that is all T1 or not, but if you have fill 12 of your card slots up with something like this, the rest of the deck you assemble I presume would be a combination resources and cards that will help you grab power or win challenges. Eventually, it will be too annoying to try and remove Long Lances and Street Waif and those events will be used on cards that will help you win challenges.
The above is just what I suspect is the irritation with facing Long Lances + Street Waif because you are probably going to have only 1 card in your discard pile for about 90% of the game.