The bingo in April would have been a good way to get them here without doing another event if that is what they were afraid of. Then we could have kept going with a new character unlock every month.
Yeah, it's not like we've ever had an unlockable Rare Hunter before. (Arkana.)
I feel like any character with a Summoning animation is pretty much confirmed to eventually be playable (and likewise, the card with the animation confirmed to eventually be obtainable if it isn't already, like Ultimate Tyranno).
Whoever said they were not going to be playable was truly mistaken. If any character has a Roaming Event then it's pretty much obvious they are going to make such characters unlockable