It isnt a panic button, the start up is to prevent it from being an "OH GOD IM BEING SHOT AT SPLASHDOWNNNNN phew, got em, that was close"
I tend to use splashdown for 3 things- panic button, surprise attack tool, and a safe super jump. Maybe then instead of speeding it up make you invincible during the startup? YES, I know that Bubbler and Kraken were removed for a reason, but this would be so brief it wouldn't even matter much.
Other buffs:
96 gal needs to get its 62 damage back. Now that defense up is gone, it wouldn't be seen as a weapon to negate defense up.
Aerospray needs a fire speed nerf STAT. It's WAY too overused.
Slosher is much better in 2 but I don't see many people playing it. Decreasing special charge could make it more appealing.
Dualies..... holy crap, they get WAY too much of an edge from the roll. I've gotten 21 kills with them on Splat Zones purely because of the roll. They should probably nerf the post-roll fire rate,
Chargers need a charge time buff because I don't see them nearly as much and it's clear they've gotten some sort of nerf.
Stop pissing on brushes. They're great combat tools if used right. Damage buff for them would bring out their combat skills more.
Clash blaster is pretty much by def worse than Luna. Range boost?
Goo tuber is impractical because storing charge really isn't that helpful. A range buff could make it more viable.
Finally, roller vertical swings need to be tied to L or A. It baffles me that it isn't.