Of course this could be bad... if Home is set to detect it. I think both options of faking and not assigning a tracker are bad. The lesser of two evils would be not assigning a tracker. It's very well possible they are looking at pokemon like solgaleo and zekrom and realizing that it's impossible for it to not have a home tracker if it was legitimate. However they may also have trackers attached to mons… so faking and using a tracker of say a litten and attaching it to zekrom would also have them detecting an illegal mon that should've been a litten.
So the lesser of two evils is not attaching a tracker. I say both are bad but using a tracker code from another mon is more dangerous. Either way they could have systems in place to detect wrong codes or no codes on a mon that should have one. From what we know now, we know that if you do not have a tracking code, you will be assigned one. If you have a duplicate it is erased. That means the best option is to have home assign one. This is also assuming that having home assign a code means the mon is safe. For all we know that code could be detected as illegal from here on out and anyone with it will have it deleted in the future. We just don't know what their capabilities are... until we do (if ever), assuming that being assigned a code from home is safer than having a code from a different mon, is the best option. They could both be bad though still.