It is amazing how people can rationalize unethical behavior. Seed times are almost always requested as "best performance", not as some hypothetical mark that a coach "thinks" his athlete can accomplish. When coaches submit a false performance mark, it is unethical.
Coaches might learn something from this example. A college coach I know wanted to enter his female 800m runner in Mt Sac last year, but the standard to enter was a best of 2:10, whereas his athlete had only run 2:11+. Rather than lie, this coach sent an e-mail to the Mt Sac meet director Scott Davis, submitting the 2:11+ as a seed time, and explaining that he felt his athlete was ready to run 2:10, but had not done so yet. Davis, grateful for such honesty, allowed the runner into the meet. The athlete ran 2:10 on that trip , and ended up something like 17th out of the 40 or so runners (all of whom supposedly were 2:10 or better).