Well, always assuming that you get caught doing this, which is unlikely unless you cause a problem for someone using this spectrum legitimately, then it would be difficult to justify anything more than a warning. After all you're using features of equipment bought in this country, from a company you could expect to comply with relevant legislation and it regards an issue that you'd have to go to a specialist forum or publication to find mention of.
If I'm still scratching my head over the issue of whether the UK models of the AEBS have the wide channel functionality disabled in firmware, even after trawling the web regarding the issue for several hours, then you can bet that your average granny doesn't have a clue the problem exists. Punishing little old ladies for problems the average Joe in the street doesn't understand tends to lose votes and therefore tends to be avoided.