By your logic, NOBODY will be able to multi-assault, as any other unit out there is FURTHER than the original declared unit (even if the 2nd unit involved is in the way). By your interpretation of the rules, I must fulfill "ALL of the stipulations for assaulting one unit BEFORE you can attempt to assault a second unit". So,
1) First model, must touch declared closest model. Done.
2) All other models in range to do so, must BTB with declared unengaged model of assaulted target. They cannot choose another target. Must maintain coherency.
3) All other models, must BTB with declared target. Must maintain coherency.
4) Cannot reach? Support
5) Cannot support? Hang around.
But here's the point: NOTHING in the above 5 steps state anything about assaulting a 2nd unit. They're steps to fulfill assaulting only the original target unit. And by the time "ALL of the stipulations for assaulting one unit" is done, all the models would have moved, and cannot "attempt to assault a second unit"...
Note that the above is WRONG, steps 2-4 at least (by most, if not all the people I know, and by most of the people I've read on the intawebs).
The key here is you can declare a 2nd target. That target becomes eligible for charging "as long as all for assaulting one unit stipulations are met"... note the difference in my statement and yours: Because I declared a split charge, BOTH units ARE Eligible Targets, and BOTH units count towards the rule of assaulting:
1) First model, must touch declared closest model of first target. Done.
2) All other models in range to do so, must BTB with declared unengaged targets, never mind if it is the first target or any other target. Must maintain coherency.
3) All other models, must BTB with declared unengaged targets, never mind if it is the first target or any other target. Must maintain coherency.
4) Cannot reach? Support
5) Cannot support? Hang around.
And that is where you and I (with paintraina on my side) differ...