To your point on potential boondoggle, I'm suggesting that it is a shorter putt and less expensive to turn a four bedroom home into a five bedroom home than it is to convert a mobile home into a four bedroom home. Don't forget, this conversion needs to occur "lot after lot" - aka mile after mile. I think it also matters who your general contractor is, and your options are fixed here: IAIS owns the property on the currently proposed route from Wyanet, IL to Des Moines and beyond while BNSF owns the path I suggested. Negotiations with IAIS have apparently been ongoing for a decade+/-, and I don't find that surprising given IAIS took over a bankrupt and dilapidated railroad in the 80's and only circa 2005 did they increase their maximum operating speed from 25-mph to 40-mph... 79-mph+ with people is a different animal. Meanwhile, BNSF has hundreds (thousands?) of miles of 90-mph passenger, the technology to maintain it there, and has a pre-BNSF history of running over 100-mph. If UP would accept upgrades to 110-mph, who says BNSF wouldn't accept same for 110-125?
Reason I focused my comments on Des Moines is I think it is the path to winning over Iowa, if there is a path. Des Moines is not only the biggest metro area in the state by far, but it is also the state capitol. As a previous commenter suggested, the state legislature needs to be on board, so perhaps the best way to get there is to benefit them upfront - not at some point potentially, maybe, down the road. Wikipedia quotes Des Moines' MSA population at 719k, more than the MSA's of the Quad Cities (382k) and Iowa City (177k) combined. Des Moines is almost exactly half of Milwaukee (1.6M), more on that in a minute.
To your point, IL plans to get to Moline (Quad Cities). They also plan to get to Peoria (398k). They could continue down the path of two host railroads (BNSF to Wyanet & IAIS to Moline... three in the case to Peoria), or they could utilize BNSF-only via Galesburg to access Moline (and Peoria). It's true that a CHI-GAL-MOL route is longer by mileage, but a 1940 CB&Q timetable shows a CHI-GAL trip time of 2h 12m. Max speed then was likely in the 100-105-mph range, so if modern equipment ran at 110-125-mph, trip times right at 2h are feasible (and would shave ~40-mins off 8 existing Amtrak trains already in that lane). Meanwhile, it's only 52-miles from GAL-MOL (and it's coincidentally 52-miles from GAL-PEO), so if those trips can be covered in no more than one hour, total trip time to MOL (or PEO) is 3h which is competitive with auto and air (with security, etc.) and even with 1950's era Rock Island timetables showing 2h 55m to 3h 20m for those destination. Then there's the added benefit of dealing with only one host railroad and no in-route handoffs. Finally, with all those destinations joining at GAL, you'd have 1.7M with high-speed access to CHI (more than Milwaukee) and better connectivity to western destinations (Kansas City, Omaha, Quincy, etc.). In fact, that 40-minute improvement would reduce CHI-KC trip times to around 6.5h which is more than an hour faster than driving.
That's not a boondoggle. That's a network.