Blessed ashes are distributed at the start of Lent as a sign of penance, and an acknowledgement of sinfulness and the need for repentance. No one would argue that someone who supports abortion needs to be repentant; there is only a question of whether or not someone who is not apparently repentant for his support for moral evils should be given blessed ashes.
One, ashes are a sacramental, not a sacrament. While there has been controversy over whether a public supporter of moral evil should be given Communion, there has been no similar consideration of whether he should be denied sacramentals such as blessed ashes. Two, while it is true that giving the impression of being a faithful Catholic while publicly rejecting Catholic morals is hypocritical, the Church does not deny sacramentals to hypocrites. The Church calls such people to repentance and hopes that whatever actual graces may be received by receiving sacramentals will be salutary for the soul of someone who needs to repent support for moral evil.