This just isn't unconstitutional. The Constititution says he has to sign the bill. It doesn't say how he has to sign it, or what implements he can or can't use. It just says he has to sign it. His signature is affixed. By his autopen. With his permission and intent. He signed the bill.
There isn't a Court in this country that is going to rule that a bill is unconstitutional because the President used a automated pen to sign a bill rather than a ball-point pen. It is a petty technicality at best. If a staffer forged his signature, with an autopen or a regular pen ... then you have an unconstitutional bill.
Does it matter whether he had to leave town? That's certainly not anywhere in the Constitution.
SnakeDoc
Its not his signature, its a facsimile ...
You cannot just willy-nilly decide what is constitutional - based on "permission and intent". You have to follow the law.
The law says that the President must sign - not a damn machine ...
If the anti-gun twits can say that the Second Amendment only applies to flintlock muskets, then the President must sign all legislation with a quill pen.