I've heard every reason under the sun as to why Suzuki quit making them, but none of them have any solid explanation other than it was more of a company decision not based on external causes.
In other words, it wasn't mandated due to lawsuits, emissions, replaced with 4-strokes, or lack of public interest in racing ATV's.
Reason being is that the banshee, a 2-stroke racing ATV continued to be produced and bought without lawsuits, emission issues, lack of interest, or "superior" 4-strokes.
Suzuki also made the RM250 (a 2-stroke dirtbike), the RGV250 and RGV500 (2-stroke street bikes) for many years after they quit producing 2-stroke ATV's, and they also kept producing the LT230 for several years after as well.
There's probably several examples that I haven't thought of to fortify this point as well.
So any arguments about emissions or lawsuits about Suzuki's 2-stroke ATV's and/or sport ATV's are nullified by those examples.
If they had to stop making them for one of those reasons, they would have stopped making all 2-strokes, or stopped making all sport ATV's...but they didn't.
The real reason Suzuki quit producing the LT's is because they stopped wanting to.
The execs probably put it to a vote and decided that 2-stroke ATV's were a dead end and shifted their efforts into other things, just like they're doing now with the little cars they quit selling in the US.
it doesn't mean their decision was a good decision, just that they felt correct in doing so, and the rest is history.
Suzuki does have a tendency to read too much into the market and jump ship before it's actually time to.