I suspect any limitations or disability would be a matter of the applicable banking regulations or bank charter. The tax code and ERISA are neutral. An employer can lend to its ESOP.
What Luke said but if the plan document is suitably vague, it is the legal Plan Administrator's responsibility to interpret the document. Review the docs, look at the SPD, and any other employee communications see if there is anything that requires or states the match be calculated one way or another. Many times, that provision is "discretionary", which can mean that the ER can decide year to year how to calculate the match.