I'm an engineering consultant. Is it "ethically conflicted" of me to support financially candidates who want to build more roads, schools, airports, ports, and subways?
This is rather like saying it is ethically conflicted for taxpayers to give money to candidates who support lower taxes.
If the candidate you are financially supporting has winked at you indicating upon his win you will be first in line for a $61 million contract to build them, yes. It is.
Nope, because a tax is by definition a government usurpation of somebody's rightful earnings. By simply pledging to reduce the level of that usurpation a candidate does nothing more than correct the imbalance that taxes create to begin with.
Contrast that with Metro and STV. Metro is spending somebody else's money. STV is recieving somebody else's money. And the reason that money is being spent by each stems directly from the fact that Metro and STV colluded to pass a referendum that would permit them to do so.