The short answer is that the treatment that was recommended to you is not necessary, and might risk harm to other organisms.

Insecticide treatment is not needed for Spotted Lanternflies, which are present throughout the state (and region) at this point. Although they can be a significant nuisance for people (with the honeydew they produce), the insects do not generally kill or stress mature trees, and while "trap trees" using pesticide can be created with their preferred host plant, the invasive Tree-of-Heaven, that is best left to professionals monitoring the population at large.

Systemic pesticides are absorbed the plant (through leaves, roots, or injected into the wood, depending on the method of application). Since they move into various tissues, there could be a risk of them contaminating flower nectar and/or pollen, which can impact pollinators. More data is needed about how frequently this happens, and undoubtedly different chemicals, in different application methods, timing, and dosages, will have different results. Plus, different insects have different vulnerabilities to the insecticide toxins.

Dinotefuran belongs to the insecticide group called neonicotinoids ("neonic" for short). They are systemic, and while dinotefuran might not last as long inside a tree (before being broken down) as, say, imidacloprid (another neonic), we don't have information about how much of a risk it poses to pollinators. Therefore, we discourage its use when it can be avoided, and Maryland has regulated neonics to only allow certified pesticide applicators for purchase and application on outdoor plants in the state. It might successfully kill lanternflies that feed on a treated tree (why they are used for the Tree-of-Heaven "trap trees"), but it won't impact the area's population for very long, in that other adults can merely fly in to an area to recolonize it.

Beech trees are wind-pollinated, as are pines, so pollinators would not be visiting the flowers much, if at all. (Some bees collect pollen from species that are primarily wind-pollinated, but we don't know of any that do so with these trees in particular.) Maple can be both wind- and insect-pollinated, but they will be finished flowering soon, if they aren't already, since they flower very early (this depends on the species of maple). Given that, a treatment to any of those trees probably poses reduced risk to pollinators, but we can't say whether or not it will be more-or-less harmless to anything not directly feeding on a treated tree's sap. Plenty of other insects chew leaves (without harming the tree), for example, that are important components of the ecosystem, feeding songbirds and other animals. Maples support lots of biodiversity, and are integral parts of our natural food web.

Squishing  lanternflies, while tedious, is a much less harmful approach to management than using a pesticide, though if one were warranted, a topical treatment of horticultural oil or insecticidal soap (as low-toxicity options) is a better choice than systemic, since you have more control over what is being exposed to the pesticide. The trade-off is that the sprays will only affect what they touch, so lanternflies out of reach will not be controlled, but at least the residues break down rapidly so they don't persist in the environment for nearly as long as a neonic might, especially if soil-applied to a tree's root zone.

Miri