It wasn’t so poisonous.

Jeremy Lin yesterday accepted the Rockets’ back-loaded “poison pill,” four-year, $28.8 million offer sheet, and it hardly created a ripple with the Knicks, who will match it. The final year even has a team option.

Ignited by having Jason Kidd agree to join their roster and become Lin’s mentor, the Knicks can’t wait to get Lin back.

“He’s their guy,’’ one NBA official debriefed on the Knicks’ strategy said. “They’ll match.’’

The Knicks officially will be presented the offer sheet Wednesday, the day the NBA’s free-agency moratorium ends, and will have three days to match it. It should take them three minutes.

Rockets general manager Daryl Morey presented Lin an offer sheet late on July 4 — calling for $5 million in the first year, $5.2 million in the second year, then backloading the deal with $9.3 million in the third year and $9.3 million in the fourth, according to a source. Yesterday, Lin’s agents tried to negotiate a guaranteed fourth year.

The final two years could have gone as high as $15 million each, but the Rockets didn’t come close to the “poison pill,’’ which would have been a $40 million whopper.

The third year of the deal is the only pill Knicks owner James Dolan will swallow because it puts him deep in luxury-tax territory, as five players would total $78 milllion — $5 million more than the threshold. In the non-guaranteed fourth year, however, the contracts of Carmelo Anthony, Amar’e Stoudemire and Tyson Chandler will have expired.

Knicks general manager Glen Grunwald will keep his word as he has said in every interview Lin would be back next season, pointing out he held the cards since he could match any offer. In fact, the belief is even the Rockets know the Knicks will match, but they could gain from sharing the pie of luxury-tax escrow money with other non-taxpaying teams.

With Jason Kidd aboard, the Knicks see him and Lin occasionally sharing the backcourt. Coach Mike Woodson, who visited Lin in California in a recruiting pitch in June, said Lin would start next season, but all bets are off now.

The Rockets are in search of point guards after trading Kyle Lowry yesterday and failing to re-sign Goran Dragic. It is plausible the Rockets made the offer sheet to Lin, once cut by the Rockets, as a publicity stunt since they are huge in China because of Yao Ming, who retired in 2011. The Rockets also could be doing Yao a favor because he is close to Lin. Grunwald had refused to make Lin an offer until he set his own price tag.

Lin withdrew from the U.S. select team earlier this week — as first reported by The Post — because of his contract uncertainty and so he can do recruiting visits. That uncertainty is over. A source said Team USA officials have asked him to come to Las Vegas to at least to support the program. The select team will practice against the U.S. Olympic team starting today.

The Lin offer sheet probably won’t change the Knicks’ thinking in matching Landry Fields’ offer sheet. The Knicks fully expect to re-sign shooting guard J.R. Smith for the 20 percent raise they are allowed — making his contract worth $2.8 million.

marc.berman@nypost.com