it's economics 101.

if you have a situation where two replaceable commodities are competing with each other on a market where demand is inelastic (like heating homes.), the cheaper one always rises to meet the cost of the more expensive one, in the long run. the reason is that producers make pricing decisions under inelastic demand, not consumers. consumers cannot do without heat to bring the price down. so, the cheaper producer may undercut the market in the short term, but will have infinite leverage in increasing prices, until it catches up to the more expensive one. and, because producers exist to maximize profit, they will do so.

in the end, buying natural gas is not cheaper than buying electricity - but it may be more profitable to sell it.

it is consequently not rational to convert to the cheaper production option, unless you can find some way to recoup the costs, quickly. and, if you're going to switch, you should ensure you can switch back at minimal effort.

what that means is that what these people should have done is keep the electrical baseboards in place, and let the tenants decide what to use based on what is cheaper at the time. and, if such an arrangement were to become widespread, the (relative) elasticity of the demand would increase, and market forces may have some effect on price.