The logic applies with the FDL as well, but applying it between a sidewinder and FDL is not fully appropriate for two reasons. First, starter configurations, even in balanced mmo games, don't always fit the realm of balance you expect later. You ideally start the player at some basic introductory level until they are ready to take off the training wheels. Second, the difference between those two ships, without engineering, is nowhere near as dramatic as what engineering provides.
There are plenty of ways to progress a player other than improving their stats in every corner. Just as a perfect example, an Anaconda will fly nowhere near as fast as an FDL and may even lose a battle against one with all engineering included, but the Anaconda will be significantly more capable of performing higher end PvE missions. That dynamic alone provides appropriate progression, not all stats +++.
If you feel like getting the final word in, that is fine, but I will not continue any more off topic ideas in here. The point was simply that removing shadows and reflections should not be considered cheating, that suggesting so would be laughable because of how much damage to balance the on-foot version of upgrading already offers with respect PvP concerns. It's akin to using macro keyboards at best, well within normally acceptable tolerances.
Agree that's enough off-topic in here, but i find really worrisome that you seem to feel that cheating is justified to compensate for certain levels of game progress that you personally are against.
Engineering is not cheating.
Now back on the topic of shader "fixes" - yes, they are cheats if they remove (or alter in other ways) the shadows that are used for cover by other players/npc
it's just simple as that.