I originally planned on selling in March but having it occupied for another year knowing that I’d save real estate commissions is appealing to the pocket .

Basically your agent's trying to make a commission and I'd find another agent. 

I realize what a jerk move it would be not to give him the commission on the sale if/when I decide to sell.

But if this company screwed over that many owners to that extent, the owners could theoretically file a joint UTPCPL complaint with the Office of Attorney General or the State Real Estate Commission.

I handled all of the paperwork for the sellers and did not take a commission.

Commission is separate.

Management fees:none as real estate agent gets his commission on rental contract renewal, so they manage for free. 

Also keep in mind non-rehab related costs such as holding costs (utilities, taxes, mortgage payments, etc) and selling costs (commissions - typically around 6% total, staging - if applicable, etc).

But even if you had to pay a commission it may be well worth it, not losing money is first priority.

No one likes to split their commission.