Is oil dilution a possibility for this car?

That is a very rare problem to have indeed.  I currently have a 2019 Civic Si with the same 1.5l EarthDreams turbo engine with almost 11k miles on it.  So far no problems in terms of what you've stated.  I wouldn't worry about, especially since the car will have warranty (at least I hope it does).  That would be a problem that would be fixed under warranty, if you happen to get a car with that problem. 

The only way gasoline is going to mix with the oil is when you have misfires and the gasoline washes down a cylinder wall and gets in the oil pan.

I could see if the turbo was oil cooled and antifreeze cooled where the coolant might get into the oil but you're telling us it's gasoline getting into the oil.

As it's rare and synthetic oil changes will eliminate the problem why are you worried? If you research enough I expect you will find scare stories for every car on the road. I also think that short trips may be the cause as a hot engine with hot oil should burn off any gas in the oil. I wouldn't be deterred from buying the car assuming your test drive was OK and the price was right.

im in uk ..never heard of this problem over here ...the honda engine is one of the best ..and strongest you can buy ..the problem ..if there is one could be because of north american very strict emissions ..your engines are choked to death  ...slower and more thirsty than our engines ..as others say ..your car would be under warranty ..so why worry?

Honda's original factory warranty is based on the VIN (i.e. the car) not the owner.  It transfers to you...Since the car has a 3y/36K bumper to bumper warranty and 5y/60K powertrain, it's a mute point for quite a while (it's based on the in-service date)

You have at least 2 years left on the warranty and maybe close to 4....

After that they will gladly sell you an extended warrant if you are still concerned.

Honestly, if it was me what I would be worried about is buying a flooded car.  You are in TX.  It's only salvaged if the owner had insurance buy it.  If it didn't have comprehensive coverage, it would have been repaired private party and there would be no record of the flood damage.

FYI - I'm a former owner of a 2004 Acura TL which they say is a trouble year for transmission... my friend is currently driving the 2006 also a trouble year = neither of us has had a problem.  Out of the thousands of cars sold, a very small percentage of people having problems makes it a "trouble year". 

If you are looking at a "trouble year" with the 1.5 Turbo just plan on having the problem!

I would suggest doing some research at safercar.gov to see what service bulletins/ recalls have been issued by Honda if you can't find a different source.

I suspect most of those having problems have been running excessive boost. The problem is not the "oil" but rings clearances and tolerances. What ever fix there is will either require an engine replacement or a engine rebuild. Not a cost I would want to absorb.

Buy a car without a turbo and without direct injection.  Problem solved.  Do not overthink it.