Strickland had over two months notice as to what the issue was. As shown by below timeline, Strikland's only defense is that he does not read his mail then!
4/16/99 all members of Congress receive letter on study from the APA.
4/21/99 Representative Joe Pitts (R) of Pennsylvania sent a “Dear Colleague” letter to all members of the House of Representatives condemning the Rind et al. study, with a copy of the Dr. Laura 4/20/99 editorial from The Washington Times.
5/10/99 The Family Research Council sent letters denouncing the Rind et al. article to all members of the House.
http://bama.ua.edu/~sprentic/607%20Garrison%20&%20Kobor-2002.htm
The second of these items is the only one I would place any emphasis on. The amount of mail flooding into a congressman's office makes it impossible for the congressman to actually read everything. However, letters from other congressmen most likely receive more attention than from your average Joe.
Now, if his staffers (who actually read most of the mail) didn't notify him of something like this, that isn't good.
However, I do prefer people don't vote when they don't know what they're voting on. The amount of spin is staggering, and if you only know the spin on something, and don't know the facts, voting on it really isn't that honorable... (note that this study really was sleazy)