Question about Low Level Quest Exotics

Hey guys! Loving the game so far on PC! Question here:

I completed the MIDA quest fairly early, and the exotic is now at light level 281. Everywhere I see states that I should have waited longer. How do I max out an exotic’s light level that I got from a quest, since I cannot infuse it with a higher scout rifle exotic because no others exist? Do I just have to wait until I get a higher legendary from the “powerful engram” reward in later weeks?

Thanks for your help in advance!