The syncopated guy shouldn't be questioned with "Why wouldn't you play simpler?" kinda questions, because he obviously doesn't want to. I know a (young) drummer who soloes excellent. Freakin' Dave Weckl. But he can't put together a steady kick-snare 2/4 beat for 8 bars. His tempo totally falls apart.  He asked me for an advice, 'cause I play in several r'n'r bands of all types and I took him to my rehearsal room and saw that he can't keep the tempo flowing. I bet it's the same thing here. Kolya, your drummer is probably frustrated with the fact that he can't follow the band successfully by keeping solid beat and therefore does what he knows best and where he feels "at home" - filling wherever possible. The man HAS to be replaced if you want a band instead of his "solo act". If he was such a character which gives "soul" to the entire band, or simply a great guy, you could consider wasting more time with him. But he doesn't sound like it from your past posts.
Cheers from Croatia, folks.

Make him listen to two songs:
1.) "Fool in the Rain" by Zeppelin
2.) "Kashmir" by Zeppelin

Point out to him that it is the same drummer, but that the styles vary greatly due to what the music calls for.  "Fool in the Rain" is tasteful, syncopated, and complex, whereas "Kashmir" is a heavy, loud, and straight.  Tell him that is exactly what you need in his playing.

If you need to, say something like "Well, if you CAN'T DO IT, I guess I'll have to find a better drummer."  Try intimidating him.  If he's extremely self-centered like he seems, he won't let you say he's not good enough.

Just my two cents

one man's soloing is another man's grooving.  listen to aja by steely dan, for example.  gadd is soloing through much of it.  or much of a love supreme, drum solo, or almost anything by the 60's miles quintet with tony, or mahavishnu, or some zappa, or ...

my point is that when there is a disagreement on what constitutes "a groove", who decides what is appropriate, the self-appointed "leader", or the players themselves?

thanks, but i've cited both "solo's" and "chops intensive" examples so what am i confusing with what?  without hearing the actual material in question it's hard to say if the problem is that he is doing "solo's with group participation", or just "chops intensive" comping.  i absolutely agree that the the drummer's job is to support the song.  but, obviously the "too syncopated" drummer believes, rightly or wrongly, that, in his own way, he is supporting the song.

my point is that different people have different ideas about what "appropriateness" is, and that it can be very presumptive for someone to expect that everyone will play the song exactly as they want it played without providing some incentive other than "i decree that thou shalt ...", and that paying for what you want is effective, arguing back and forth is less so.

The AJA example is just one song. We are presumably talking about a body of work here. The rest of the AJA album includes some simple groove playing. Likewise, Gadd doesn't impose a chop heavy approach in all his work.
The problem here is that the drummer in question is not (arguably) over playing on one or two songs, but over an entire repetoire.
Regarding this argument about being dictated to or not. My quick solution is to find a band that likes busy drumming. Don't impose busy drumming on a group of musicians who don't want it (as apparently in this case).
As an overview of this topic.....
i hear way more complaints about drummers over-playing on my world travels. hardly ever anything about a person under-playing. Therefore my sympathy for drummers who want to stretch out, no matter the consequences, is in rather short supply.  

This is my for what it’s worth opinion.  Don’t get  bogged down in the “straight eighth notes on the hi hat argument.”  No one ever bought a record because of a great hi hat track.  I subbed with a band once that insisted on straight eighths on every song including Aretha Franklin’s “Rock Steady.”  If you’ve ever seen the old Saturday Night Clip where Ray Charles tries to teach four rich white kids how to sing “What’d I Say”  well that’s what it sounded like.  I’ve done studio jobs where all I did was to lay down a swinging hi hat part because the straight eighths on the rhythm machine parts made the song too stiff.
That said, I been accused of being too steady with my rhythms and some musicians won’t work with me because my timing doesn’t vary enough.  I think it’s just a matter of finding like minded musicians.