Dear Product Manager, you can't avoid doing rogue projects.
Sigh... Leading the team to do things you were explicitly told not to do.
If you've been a PM long enough, then you would have been at this crossroads before. You are absolutely convinced about something; maybe a way of implementing something, maybe a tactical manoeuvre; but then someone in "upper management" says "don't do it". Or sets unending high jumps of things you must have in place before exploring the direction. Can be very frustrating.
It's even more frustrating when the entire team is convinced it's the right thing to do. Maybe even some customers are aligned. But this internal stakeholder, who doesn't have half the facts, just wants to be a spanner in the works. Or is simply covering their own ass. Or protecting some imaginary turf.
Often as a PM, you end up having one of 3 options.
a. Give in and move on. Path of least resistance.
b. Keep at it, scale every high jump and finally convince.
c. To hell with it! Go round him. Or her.
Personally, I am very biased towards the third option. For the following reasons.
I believe in the saying that it's much easier to obtain forgiveness than it is to get permission.
Any Product Manager who goes with the first option is probably not going to get any tangible results in her career and will mostly just evolve into a project manager with no mind per se of his own. In my little experience, there'd be no tangible outcome he'd be able to point to. Everything good comes with resistance from some quarters. So, using option one all the time is a no no. If you care about being a PM that ships good stuff and executes great strategy; rather than that management boy who just does what he's told.
Option two is the honorable one... but emm... Good luck with that!
With option three, take a risk. The fear of failure (and it's implications) will force you to think and rethink (and RETHINK) your chosen approach or project. Genuinely consider their pushback with an open mind. The deeper you re-evaluate the position, the more your conviction shines through and infects your execution team if still valid. In a team of techies and product people, passion is a mad ass catalyst.
When it works (if it does), it'd be a solution/direction with your clear signature which earns you more credibility coins for future product decisions. Every PM needs this. Remember that PMs are people who are meant to lead without authority... As such influence is one of the tools you use to get people to follow you. Credibility, and prior successes attributed to you and your choices go a long way in earning you these stripes.
There's a risk though: Apart from the risk of failure (after all, you didn't follow clear instructions), depending on the culture of your organisation, you may have earned an enemy that will start setting leg for you in future. Worse, if it's some asshole with a big ego, he may make you shut down the entire operation and not go live, just to prove a point. This is more demoralizing for the team and yourself than not being allowed to do what you wanted to do in the first place. I've been there. Painful.
I believe a Product Manager that will do well, needs to come into her own and take some risks and responsibilities. Break some rules... or end up just becoming a Management (or stakeholder) errand boy, who often will have no tangible results to point to after a while.
Don't do this too often though. For obvious reasons. [In ChiGurl's voice] You gonna be what..? You gonna be sacked!
Disclaimer: As you know by now... take any opinions from me at your own peril, but I believe in this one.