We owe it to the audience, fellow band members, etc., to fight for the correct signal chain that allows us to produce the intended sound such that the pieces we play sound as intended (as far as is possible) and we can play at our best. So if someone asked me to do this I would try to reason with the sound engineer as I don't think the proposed option is the best way to serve the music. Sometimes, you do have to be pragmatic but using a keyboard amp is a very suboptimal way to do it unless it has really good bass extension and is of high quality and the sound produced by it, as demonstrated in a sound check, is appropriate. I certainly don't think suggestions such as taking a DI before pedals is appropriate if the pedals are a part of your sound. That's like banning the trumpet player from using a mute or saying that falsetto is not allowed in a rendition of Bohemian Rhapsody.