When bureaucrats can decide at the last minute to change the rules, a country no longer is governed by laws but by unelected people.  Throughout this whole approval process the companies followed the rules, provided all the information that the bureaucrats demanded/wanted, altered the route when requested and received final approval.  Then as the pipeline is being built, unelected 'environmentalists' held everyone hostage and the bureaucrats caved.  

What message does that say to business about spending money in the US (and it will extend to Canada as well)?

If the problem was running the pipeline under an aquifer, then that issue should have been addressed BEFORE approval (and I suspect that it was) or the bureaucrats failed in their basic due diligence (and surprise, surprise, surprise none of them will be held accountable in any way up to and including losing their jobs or paying a penalty).