It's a call spread, so it protects against dilution to 607.50. Curiously, shareholders suffer double-dilution above 607.50. Well, except Musk. That's the point where his comp package kicks in and gives him a boatload of new shares. Normal metrics for a convert would have warrant strike around 460 with only single dilution. That would have brought in roughly the same 175m, but Musk would have suffered dilution along with his fellow shareholders.
Anyway, cost to hedge dilution entirely is ~8.6%:
1840 - 476 = 1364 net proceeds
1364 with 18.4 semi-annual coupon and 1840 due on maturity = 8.6% APR
It's actually a bit higher since underwriting fees reduce net proceeds. This is in line with the 2025 bonds which trade around a 8.4% ytm.
Selling the 607.50 warrants reduces their cash APR to 5.9% (~6% including fees). They should recognize something close to the 8.6% as interest expense, though. That's about 30m the first few quarters climbing to ~40m the last quarter. The old converts were about 11m the last few quarters.