The regulation is pretty clear that some type of weight has to be on the bottom of the setup to be illegal. I can't see any CO ever writing a ticket for a rig with no weight of any kind on the bottom. It wouldn't be a very productive snagging rig. You still might have a hard time getting a consistent and straight answer from the MDNR regardless because of their concern about snagging and about making exceptions for anything close to the long-line snagging rig.
We have been told a lure is not a weight by some MDNR so a tube jig on the bottom does not meet the definition of the illegal rig. You definitely won't get a consensus vote on this from the MDNR. You won't get an 'exemption' in writing either, but you should not get a ticket if you aren't trying to snag - don't make snagging movements.
The main issue would be for tournament anglers. If you use the rig in a tournament on Michigan waters and get protested, you'll probably get dq'd. It would blow my mind though if any tournament director every dq'd someone for using something with no actual weight on the bottom like a jighead or piece of lead or other metal.
For non-tournament fishing, you should be okay although I wouldn't use the rig in the middle of a salmon/steelhead/walleye run just in case.