If they aren't willing to abide by the terms of a first round draft pick, they should trade their first round pick and only draft in later rounds.
It’s not unprecedented, it’s just not usually done that way for top 10 picks. Of course part of this is the team. Because the Chargers stink when they do something unusual everybody figures it’s dumb. If this was the Pats were holding this line everybody would be talking about how smart they are for not doing the usual thing.
They’re perfectly willing to abide by the terms of a first round draft pick, they just don’t want to take more risk for a higher salary player than they’d normally do for a lower salary player. It’s actually kind of reasonable for a team that’s going to pay more signing bonus to not also want less ability to recoup.