Ask a professor to attend a conference
Probably the faculty person's plans are already made, months in advance, so your asking will have no impact on their actual plans. Possible, but not likely.

That is, if they'd not already planned to attend, they had reasons to not do so, or insufficient reasons to do so, and these reasons will probably not be changed by your own attendance... especially when the faculty person has made a recommendation.

Yes, as often, there is some risk of accidental misunderstanding about motivations, personal versus professional. The usual irony is that only the scrupulous, honorable people worry about such things... :)  But, in any case, I'd think that the on-the-mark question would be "are you yourself going to be there... for me to bounce questions off?"

As in many situations, asking the actual operational question, rather than any sort of circumlocutious persiflage, is ... good. In fact, the tone of many circumlocutions can accidentally/inappropriately suggest unintended intentions... of course.

This is yet-another one of those situations where worrying about "coded" communication is not productive. Be forthright.