A few things to consider, but first a question.

Are you alrady having wheel alignment and spoke problems, or is this just something the shop person said?

In any case, consider that the overall design standard for bikes is based on riders who weight less than 200#s, and building heavy duty enough for heavier riders would make the entire bike heavier than necessary for the typical rider. That doesn't mean you automatically have problems, but you will have more than average.

It's analogous to buying a 1-ton pickup truck, and using it to haul 1.5 tons of equipment daily.

Also consider that production wheels original to bikes, are rarely as well built as those built by hand in the after market. So if/when your wheels start giving you problems, you should be able to find a decent local builder (or order from a specialty builder) who can use your hubs and build a wheel more ideally suited to your weight. Ironically, this wheel can even end up being lighter than what you have now, so it's win/win (except for the dough).

Meanwhile, there are things you can do for yourself.

1- adopt a smoother riding style, turning the pedals at a higher cadence (using a lower gear) as this lowers the peak torque on the wheel.
2- stay alert to pavement conditions, steering around bumps and potholes hen possible, or standing with your knees flexed to let the bike float over them without having to lift your weight (you are the suspension system).
3- avoid rocking the bike when standing or climbing steep hills. The wheels are much stronger for the normal radial (vertical) loads than they are for the side loads that rocking imparts.
4- be attentive to loose spokes, or mis-alignment, and deal with it sooner rather than later. In wheel care, a stitch in time..... really makes a difference.