Speaker honorarium - is this Pay?

My husband (a professor, U.S. citizen) will speak for one session at a conference and will receive a small honorarium (as well as having his flight expense paid). He is just one of many professors giving short talks about their papers during the one-day conference. The information from the conference organizers specifically mentions that people from U.S. for a "short stay" do not require a visa, and I know a short stay visa-waiver is also fine for attending a conference. However, the embassy web site says you need a visa if you are paid for anything at all. So does getting a speaker honorarium count as being paid for visa requirement purposes? Anyone experience this?

http://www.immi-moj.go.jp/tetuduki/zairyuu/qa.html
Ｑ１　「観光」目的で来日しましたが，働くことはできますか。
Ａ 観光の活動は，在留資格「短期滞在」に含まれ，この在留資格では入管法施行規則第１９条の３に定められている「臨時の報酬」等に該当する報酬のみを受ける活動を行う場合を除いて働くことはできません。
since your case is 「臨時の報酬」, you don't need to have a working visa.
generally speaking, income tax will be deducted from your 「臨時の報酬」(probably 20%, because of non-resident).

The honorarium is more like enabling him buy his lunch and beer, it's paid expense not income
Don't bother about the visa and have fun

My cousin- also American citizen and prof in NUS does this all the time