The only solution I can see which would allow you to save face and yet still decline the job is to inform them that you aren't happy with the T&Cs and will only accept the job if they are renegotiated to your satisfaction.
If they decline (as is likely) you have a valid reason for declining which shouldn't burn future bridges.
If they accept then you have the job you wanted all along.
If they decline (as is likely) you have a valid reason for declining which shouldn't burn future bridges.
If they accept then you have the job you wanted all along.