That's a bit of an exaggeration. From the description of the bill on Rep. Carter's website, it's meant to encourage the purchase of gun safes and other locking devices; it doesn't make possessing or using them mandatory.
That said, you're right that the up-to-$1200 tax deduction is yet another subsidy for the relatively well-to-do.
And as critics of the bill point out, it's a pretty small step from encouraging something to requiring it.
"Once the writer in every individual comes to life (and that time is not far off), we are in for an age of universal deafness and lack of understanding."
(Milan Kundera, Book of Laughter and Forgetting, 1980)