windshield install question

talked to a guy yesterday who has done auto restorations as a buisiness and is now retired from it. i asked him if he would be willing to come over and help me install my windshield. after looking at my valiant he said he would. i showed him my tubes of sealer and asked him if i should get more, he said i dont need it. hmm? everywhere i read said to use sealer, he said he would use a rope to seat the seal and he has done alot of them and never had one complaint about a leak. when i spoke to a man at a local glass shop a few months back he said i would need about 3 warm days in a row (mind you i do have a garage) he also said i would need sealant. no one else will come to the house and this guy is very confident in his skills. he seems very professional also. do i not need sealer or do i?