When i did ART (Backmount, not SM) I was told it's preferable to have an off-board Suit inflate, but if that's not an option, then the first alternative is to use suit inflate off of the deco bottle. So yes, i'd say that it's ok to do it, just not the ideal solution, but certainly better than running suit inflate from your TX cylinders.
NOTE: Obviously, remember to add enough gas to your deco bottle to account for the extra gas used! As a general rule, a suit inflate cylinder is a 1 or 1.5L cylinder, filled to max 232bar (sorry i'm UK, don't know in PSI) so working it back to litres, i'd say you need to add at least an extra 230 litres to your deco cylinder (assuming an Ali 80, that would be an extra 21 Bar, or an extra 33 Bar if using a 7L deco cylinder) on top of the gas planning you've done for the deco gas required to ensure you dodn't use any of the deco/reserve deco gas you've planned for the dive.
Hope that helps, and hope it makes sense....